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Here, we report a case of a female adult patient presenting with fleshy lesions on her scalp who underwent elective excision, and two separate lesions were identified on histopathology. She was found to have an unusual concurrent presentation of syringocystadenoma papilliferum (SCAP) and basal cell carcinoma, emphasising the importance of differential diagnosis in cutaneous lesions. While SCAP is benign, the presence of basal cells necessitates careful monitoring and appropriate treatment. Factors contributing to the simultaneous occurrence of these lesions, such as genetic predisposition or environmental factors, warrant further investigation. Clinicians should be aware of the potential for concurrent skin lesions, particularly in sun-exposed areas. Comprehensive evaluation and management are crucial to ensure appropriate treatment and follow-up for patients presenting with multiple skin tumours., Competing Interests: Competing interests: None declared., (© BMJ Publishing Group Limited 2025. No commercial re-use. See rights and permissions. Published by BMJ Group.)

Spiradenomas are benign cutaneous adnexal neoplasms with sweat gland differentiation that can manifest a broad spectrum of histomorphologic appearances. While they show a characteristic histopathologic phenotype and clinical management involves surgical excision with a low risk of recurrence, there have been unusual histopathologic variants of spiradenoma reported, including cases with adenoid cystic carcinoma (ACC)-like changes. Primary cutaneous ACC is a low-grade malignancy presenting as a subcutaneous mass with the potential for local invasion, perineural invasion, and high rates of local recurrence after excision. The diagnosis of spiradenomas with ACC-like features can be challenging, especially when only the ACC-like component is present for evaluation. A retrospective analysis of 21 cases of spiradenoma with ACC-like changes were obtained from large academic institutions, was performed, and summarized below. All cases showed background of conventional spiradenoma, and the ACC-like areas represented a component in all lesions. The percentage of ACC-like component ranged from 5% to 40% in all cases. The ACC-like component was multifocal and without pleomorphism, perineural and/or vascular invasion, necrosis, or increased mitotic activity. MYB translocation and protein expression was studied in 16 cases by fluorescence in situ hybridization, polymerase chain reaction, and immunohistochemistry. All studied cases were negative for MYB / NFIB , MYB L1, and MYB F by fluorescence in situ hybridization and polymerase chain reaction and 3 cases were positive for MYB expression by immunohistochemistry. Our study expands on spiradenomas with ACC-like features that ought to be considered in the differential diagnosis of cutaneous neoplasms such as primary cutaneous ACC. Our results indicate that a thorough histopathologic inspection and strict application of well-defined histologic criteria are necessary to support the diagnosis of this unusual histopathologic variant. These tumors can be difficult to diagnose, and awareness of their histomorphologic spectrum will facilitate definitive diagnosis and avoid misdiagnosis with other conditions., Competing Interests: Conflicts of Interest and Source of Funding: The authors have disclosed that they have no significant relationships with, or financial interest in, any commercial companies pertaining to this article., (Copyright © 2023 Wolters Kluwer Health, Inc. All rights reserved.)

Competing Interests: Competing interests: None declared.

Endocrine mucin-producing sweat gland carcinoma (EMPSGC) and primary cutaneous mucinous carcinoma (PCMC) are rare low-grade neoplasms thought to arise from apocrine glands that share many histological features and are proposed to be on a single histopathologic continuum, with EMPSGC as the in situ form that may progress to the invasive PCMC. Management involves a metastatic workup and either wide local excision (WLE) with greater than 5 mm margins or Mohs micrographic surgery (MMS) in anatomically sensitive areas. We present 2 cases of EMPSGC and 3 cases of PCMC and review their clinical and histopathologic features, differential diagnoses, and treatment.

Background: Hidradenocarcinoma is a rare malignant sweat gland tumour, characterized by a slow but aggressive course, with high rates of local recurrence and metastasis. Due to its rarity, histological criteria and therapeutic guidelines are poorly defined, posing a major challenge for clinicians and pathologists., Objectives: To present two new cases of metastatic hidradenocarcinoma as well as a review of the literature., Materials & Methods: We describe two case studies and a review of the literature based on a search using the MEDLINE (PubMed) electronic database., Results: The first patient was a 61-year-old woman with a perimamillary hidradenocarcinoma that arose from the malignant transformation of a benign childhood lesion and developed regional lymph node metastases after wide excision and adjuvant radiotherapy. The second patient was a 63-year-old man who developed cutaneous and renal metastases several years after the complete excision of a lumbar hidradenocarcinoma. As far as we can ascertain, kidney metastasis from hidradenocarcinoma has not previously been described., Conclusion: Most authors recommend wide excision as the treatment of choice for hidradenocarcinoma, however, optimal adjuvant therapy remains to be determined. Our cases add to the limited knowledge available, but high-quality studies to find new effective treatments are needed.

Abstract: Hidradenocarcinoma (HAC) is a rare adnexal tumor associated with the potential for locoregional recurrence and systemic metastasis. The clinical appearance of HAC is nonspecific, frequently presenting as a solitary firm subcutaneous nodule or plaque on the head and neck region or distal extremities. These tumors show histomorphologic heterogeneity, as they can be low and high grade. Distinguishing HAC from hidradenoma, especially the low-grade variant of HAC, can be challenging as both tumors can show histologic overlapping features. In this article, we describe a case of a 33-year-old patient presenting with a low-grade HAC of the plantar foot who was subsequently found to have lymph node metastasis., Competing Interests: The authors declare no conflicts of interest., (Copyright © 2023 Wolters Kluwer Health, Inc. All rights reserved.)

Abstract: A 43-year-old woman presented with a palpable, pruritic, minimally painful right vulvar lesion. Physical examination revealed approximately 2.0-cm tender nodule at 70' clock in the right labia majora. Histological sections of the excision specimen showed an unremarkable epidermis with large, well-circumscribed dermal proliferation with extension to the reticular dermis. Within this proliferation are small solid and ductal structures relatively evenly distributed in the sclerotic stroma. The epithelial elements consisted of monomorphous cuboidal cells and assumed round, oval, curvilinear, or have other peculiar geometric shapes, including "comma-like" or "tadpole"-like configurations. The tumor cells were positive for CEA, EMA, and estrogen receptor and negative for progesterone receptor. The clinical presentation and the deep extension of the tumor were similar to the microcystic adnexal carcinoma. Although a syringoma generally presents with multiple lesions and usually involves the superficial dermis, a syringoma with deep extension was favored based on the lack of follicular differentiation, atypia, mitoses, and perineural invasion. Microcystic adnexal carcinoma and syringoma have a morphologic overlap and are misdiagnosed in 30% of the cases. Thus, it is exceptionally important for pathologists to be aware of and be able to distinguish these entities. To the best of our knowledge, this is the first case of a solitary, painful vulvar syringoma with deep extension., Competing Interests: The authors declare no conflicts of interest., (Copyright © 2022 Wolters Kluwer Health, Inc. All rights reserved.)

Abstract: Eccrine syringofibroadenoma (ESFA) is a rare benign skin adnexal lesion of the acrosyringium of eccrine sweat ducts. Reactive ESFA, a subtype of ESFA, is usually associated with non-neoplastic cutaneous dermatoses or neoplastic skin tumors. Clinically, the lesions can be solitary or multiple, pink, or skin-colored coalescing papules or nodules of variable sizes. Histopathologically, this tumor is composed of numerous anastomosing cords of monomorphic cuboidal epithelial cells with eccrine duct formation. The association of reactive ESFA with benign conditions, such as psoriasis, diabetic polyneuropathy, scars, and leprosy, has been reported. However, the association of reactive ESFA with malignant tumors is extremely rare, with very few cases reported in the literature. We present a case of a 72-year-old woman who developed reactive ESFA associated with Merkel cell carcinoma excision scar. The ESFA tumors developed in the area of the surgical graft 10 months after the Merkel cell carcinoma had been excised. New ESFA tumors have continued to appear in the scar on a yearly basis while, so far, has been no recurrence of the original tumor. However, the presence of new tumor growths in the area suggested the possibility of recurrence of the Merkel cell carcinoma. That possibility was enhanced by the fact that PET scans revealed hypermetabolic activity in the ESFA papules., Competing Interests: The authors declare no conflicts of interest., (Copyright © 2022 Wolters Kluwer Health, Inc. All rights reserved.)

Background: Mohs micrographic surgery is an established technique in the treatment of cutaneous neoplasms. It offers higher cure rates and the main indications are non-melanoma malignant skin tumors. Few studies have been performed on the treatment of rare tumors through this technique., Objective: To study rare skin tumors and rare variants of basal cell carcinoma and squamous cell carcinoma submitted to Mohs micrographic surgery in a tertiary service in relation to frequency, disease-free evolution, and applicability of this surgical procedure for this group of tumors., Methods: This was a retrospective observational study including rare skin tumors and less common variants of basal cell carcinoma and squamous cell carcinoma treated using Mohs micrographic surgery, between October 2008 and April 2021., Results: During the study period, 437 tumors were treated using Mohs micrographic surgery, and 22 (5%) rare skin tumors were selected. The tumors comprised three dermatofibrosarcomas protuberans, two atypical fibroxanthomas, two spiradenomas, two hypercellular fibrohistiocytomas, one primary cutaneous adenocarcinoma, one trichoblastoma, one porocarcinoma, one chondroid syringoma, one cutaneous angiosarcoma, one Merkel cell carcinoma, and one sebaceous carcinoma. Six other cases of rare basal cell carcinoma variants with trichoepitheliomatous differentiation, metatypical basal cell carcinoma, and clear cell squamous cell carcinoma were included. There were no cases of recurrence after an average of six years of follow-up., Study Limitations: This is a retrospective study on rare neoplasms carried out in a single referral center, and this surgical technique isn't widely available in the public service., Conclusion: This retrospective case series showed that Mohs micrographic surgery is an appropriate treatment for rare skin tumors. They corresponded to 5% of the tumors treated by the technique during a 12-year-period, with no recurrences identified., (Copyright © 2022 Sociedade Brasileira de Dermatologia. Published by Elsevier España, S.L.U. All rights reserved.)

Abstract: Sweat gland carcinoma with neuroendocrine differentiation (SCAND) is a newly proposed tumor entity of primary cutaneous apocrine/eccrine adnexal tumor with neuroendocrine differentiation. The histopathologic variations are not yet well known. In this article, we present a case of SCAND mimicking male breast cancer and syringocystadenocarcinoma papilliferum. A 68-year-old man presented with a reddish 12-mm nodule on his left areola. No lymph node or distant metastases were observed. The patient was disease free 1 year and 9 months after the tumor was surgically resected but died of cerebral hemorrhage. Histopathological examination revealed a predominantly intradermal tumor with marked syringotropism, mimicking a component of mammary ductal carcinoma in situ. In addition, another tissue section displayed a cup-shaped papillated tumor with syringocystadenocarcinoma papilliferum-like features, which were also seen because of marked syringotropism. Diffuse immunoexpression of cytokeratin 7, cytokeratin 19, chromogranin A, synaptophysin, INSM1, estrogen receptor, carcinoembryonic antigen, epithelial membrane antigen, and GATA3 was observed in the tumor, but no BRAF immunoexpression was seen. The present case would help us to understand the histopathological variation and differential diagnosis of SCAND. The histopathological diagnosis of male breast cancer or syringocystadenocarcinoma papilliferum should be made by ruling out SCAND., Competing Interests: The authors declare no conflicts of interest., (Copyright © 2022 Wolters Kluwer Health, Inc. All rights reserved.)

Nodular hidradenoma is a cutaneous adnexal tumor of sweat gland origin, characterized by its diverse but overlapping histomorphologic features with other skin tumors. In addition, distinction of benign hidradenoma and its malignant counterpart hidradenocarcinoma can be challenging, especially in prognostic prediction. We retrospectively reviewed pathological features of 29 cases, including benign nodular hidradenoma (n = 17) and hidradenocarcinoma (n = 12), with clinical follow-up ranging from 18 to 216 months. Genomic copy number variation (CNV) was studied in selected cases (n = 18) by single nucleotide polymorphism microarray. None of the benign hidradenomas (0/17) or low-grade hidradenocarcinomas (0/6) had recurrence or metastasis after complete excision, whereas all 6 high-grade hidradenocarcinomas (6/6) showed locally destructive disease, recurrence, or local metastases. In benign hidradenomas, CNV abnormality was absent in all clear cell hidradenomas (0/5) but was detected in a considerable portion of poroid hidradenoma (3/5), with number of abnormalities ranging 2, 4, and 9. In malignant cases, regardless of morphological classification, both low-grade hidradenocarcinomas demonstrated limited CNV abnormalities in 2 areas (2/2), whereas all high-grade hidradenocarcinomas contained 8 or more CNV abnormalities (6/6). No disease-associated death was recorded in the cohort except one case was lost to follow-up after the development of metastatic disease. Overall, the findings support that genomic CNV abnormalities may serve as a sensitive but less specific tool in detecting malignancy in these tumors, and potentially have a role in predicting clinical behavior particularly in the tumors of nonporoid morphology., (Copyright © 2022 Elsevier Inc. All rights reserved.)

Abstract: Digital papillary adenocarcinoma is a malignant adnexal tumor with a predilection for acral sites. Hidradenoma is a benign solid and cystic sweat gland neoplasm with focal ductal and glandular differentiation and good outcomes. Hidradenomas can occur at acral sites and show papillary structures; for this reason, they are included in the differential diagnosis of digital papillary adenocarcinoma, and immunohistochemistry is a valuable tool in this scenario. We described a case of a 43-year-old man with an epithelial tumor showing papillary structures in the intermediate phalanx of the fourth finger. There was diffuse positivity for p63 and negativity for S100 protein, suggesting that this tumor was an acral hidradenoma with papillary structures., Competing Interests: The authors declare no conflicts of interest., (Copyright © 2022 Wolters Kluwer Health, Inc. All rights reserved.)

Abstract: Moll gland is a modified tubular-shaped apocrine sweat gland, which is located on the margin of the eyelid. Moll glands are also known as ciliary glands. The function of these glands was not well known for a long time. However, based on the different studies, it was proved that Moll glands are active from birth and have local immunologic function producing immunoglobulin A. We present a case of Moll adenocarcinoma, a type of apocrine carcinoma, arising from the right upper eyelid of a 57-year-old man. Although Moll gland cysts are frequently seen, this type of adnexal malignancy is extremely uncommon. These tumors can have variable presentation and behavior from less invasive forms to highly malignant metastatic recurrent lesions., Competing Interests: The authors declare no conflicts of interest., (Copyright © 2022 Wolters Kluwer Health, Inc. All rights reserved.)

Mixed tumour of the skin is a rare entity also known as chondroid syringoma and pleomorphic adenoma. These usually present as slow-growing skin nodules with a smooth surface, clear boundaries, and no ulceration. Case series exist describing pleomorphic adenomas in the periocular region including the lids and orbit, separate to the more familiar lacrimal gland pleomorphic adenoma. These may arise from accessory or ectopic lacrimal gland tissue but in the eyelids are more likely to arise from sweat glands in the skin. Histopathological analysis of these lesions is important to identify complete excision, minimising recurrences and in identifying rare but potential malignant transformation. We describe the clinical features and outcomes in three cases of pleomorphic adenoma with two at the medial canthus (including one recurrence) and one in the brow region.

From the first report in 1969 to the present day, diagnosis of eccrine porocarcinoma, also known simply as porocarcinoma (PC), remains a challenge. This review presents a concise update of the history, pathogenesis, epidemiology, diagnosis, management and prognosis of this rare sweat gland neoplasm. PC differentiates towards the intraepidermal spiral ducts in the eccrine gland, is more common in people aged > 60 years and often affects the head, neck and legs. PC presents as a dome-shaped papule, plaque or nodule growing over weeks to months. The exact incidence of PC is unknown but appears to be rising. Diagnosis is difficult because of variable presentations and similar clinical and histological features to cutaneous squamous cell carcinoma. Management involves removal of the tumour, usually using wide local excision or Mohs micrographic surgery. Prognosis is poor, with PC recurring after surgery in 35% of cases. Given the lack of standardized protocols and risk profiles, further studies would help improve the understanding of PC., (© 2022 British Association of Dermatologists.)

Background: Spiradenocarcinoma is a rare skin adnexal neoplasm that may behave aggressively. It is often associated with a benign slow-growing spiradenoma that has undergone malignant transformation. Given the paucity of cases in the literature, there is a lack of consensus on treatment., Methods: The terms 'malignant spiradenoma' or 'spiradenocarcinoma' were systematically used to search the PubMed, MEDLINE and Google Scholar databases. A total of 182 cases of spiradenocarcinoma were identified as eligible for this comprehensive literature review., Results: Spiradenocarcinoma was commoner in older age and Caucasian race. In most cases, surgical excision for local disease is the mainstay of treatment. Lymph node dissection is usually reserved for those with suspected or confirmed lymph node metastases. High rates of local recurrence (20.8%), metastasis (37.4%) and mortality (19.1%) were identified, prompting some authors to suggest regular follow up including chest X-rays and liver function tests., Conclusions: Patients with spiradenocarcinoma may benefit from a magnetic resonance imaging and fluorodeoxyglucose-positron emission tomography/computed tomography to establish the extent of disease. We recommend wide local excision as the treatment of choice to achieve surgical margins of ≥1 cm, with node resection to be determined on a case-to-case basis. Regular follow up is important given the high rate of local recurrence, metastasis and mortality. This should include an examination of the regional lymph nodes. Further research is required to refine an evidence-based approach to spiradenocarcinoma., (© 2021 Royal Australasian College of Surgeons.)

Squamoid eccrine ductal carcinoma (SEDC) is a rare and under-recognized primary cutaneous tumor with a high risk for local recurrence and metastasis. The tumor has a biphasic histologic appearance consisting of a superficial portion indistinguishable from squamous cell carcinoma (SCC) and a deeper component demonstrating eccrine ductal differentiation. Because of superficial sampling, SEDC often is misdiagnosed as SCC during the initial biopsy. The diagnosis usually is made during complete excision when deeper tissue is sampled. Confirmation of the diagnosis can be achieved by immunohistochemical positivity for carcinoembryonic antigen (CEA), epithelial membrane antigen (EMA), cytokeratin (CK) 5/6, and p63. In this article, we review the clinical and histologic details of 5 patients with SEDC who underwent successful treatment with Mohs micrographic surgery (MMS) at a single institution between November 2018 and May 2020. We also review the histologic patterns that helped distinguish SEDC from SCC upon complete excision. Our findings support the use of MMS as the treatment of choice for SEDC, given that all of the patients we reviewed required more than 1 Mohs stage for complete tumor clearance, and none demonstrated evidence of recurrence or metastasis after a mean follow-up period of 11 months.

Solid-cystic hidradenoma is a benign cutaneous tumor that is most commonly found in the head, neck, trunk, and upper extremity regions of patients in the middle to older aged groups. Presentation on lower extremities and in particular on the foot is uncommon. Nodular hidradenomas represent a dermatological pitfall, being difficult to differentiate from basal cell carcinoma and melanoma. We report on a 53-year-old male patient with a pigmented nodular hidradenoma on his ankle that was surgically removed. We discuss histopathology and differential diagnosis of this eccrine tumor of skin. This is the second reported case in the English literature.

Background/objectives: Primary cutaneous mucinous carcinoma (PCMC) of the head and neck is a rare pathologic entity that is an adenocarcinoma of the eccrine sweat glands. Though it has low metastatic potential, it does have a significant recurrence rate. Due to its rarity, its clinical features are not well-known., Methods: The authors searched the National Cancer Database (NCDB) for all cases of PCMC with primary sites of the skin of the head and neck confirmed histologically diagnosed from 2004 to 2016. Those with missing survival information were excluded. Kaplan-Meier (KM) and Cox proportional-hazards models were used to analyze the epidemiology and survival outcomes of PCMC., Results: The authors analyzed 289 cases. Females were more commonly affected (58.8%; P < 0.05) with the most common primary sites being the eyelid (41.9%) and scalp/neck (25.3%). The average age of diagnosis was 63.8 years (± SD 12.5). Almost all patients received surgery as standalone treatment (92.7%) with wide local excision being the common surgery performed (36.3%). Mohs surgery represented 15.2% of surgically treated cases. Mean overall survival (OS) was 11.4 years with 5-year and 10-year OS being 85.0% and 78.0%, respectively. Most cases were localized at diagnosis with only 2% metastatic at presentation. KM analysis indicated that surgical procedure type, age, tumor diameter, Charlson-Deyo Comorbidity Score, facility type, and stage were significant predictors of OS (P < 0.05). Cox proportional-hazards analysis did not reveal independent association of the aforementioned factors with OS., Conclusion: Primary cutaneous mucinous carcinoma has an excellent prognosis with 98% of cases being diagnosed in Stage I and Stage II. As most cases present in the eyelid, special attention should be given to surgical treatment to ensure optimal aesthetic outcomes in this sensitive region. This study represents the largest cohort of head and neck PCMC studied to date., Competing Interests: The authors report no conflicts of interest., (Copyright © 2020 by Mutaz B. Habal, MD.)

An 81-year-old woman presented with a progressively enlarging indurated, firm lesion encompassing one-third of the left upper eyelid. Four years prior, a similar lesion at that same site had been excised and diagnosed as a basal cell carcinoma. The patient underwent a full-thickness excision of the lesion with frozen section, cryotherapy, and reconstruction. A free tarsal graft and hard palate composite graft was used to reconstruct the posterior lamella. A Mustarde myocutaneous rotational flap was used to reconstruct the anterior lamella. Histopathology illustrated nests of pleomorphic basophilic cells with varying mitotic activity and immunohistochemical staining consistent with eccrine porocarcinoma. This case highlights similarities in the presentation and appearance of basal cell carcinoma and periorbital eccrine porocarcinoma. It is possible that there was de novo development of the 2 tumors on the eyelid or recurrence of a misdiagnosed eccrine porocarcinoma. Eccrine porocarcinomas are rare malignant sweat gland tumors associated with a risk of recurrence after excision and metastasis., Competing Interests: The authors have no financial or conflicts of interest to disclose., (Copyright © 2020 The American Society of Ophthalmic Plastic and Reconstructive Surgery, Inc.)

Spiradenocarcinoma (SC) is a very rare malignant skin adnexal tumor with sweat gland differentiation that develops from a pre-existing spiradenoma, cylindroma, or hybrid tumor called spiradenocylindroma, or arises de novo. We present two exceptionally rare SC cases showing sarcomatous differentiation; we also discuss the clinicopathologic features of SC, as well as its differential diagnoses and available therapeutic modalities. Given the aggressive behavior of SC, rapid diagnosis and complete removal of the tumor with tumor-free margins is mandatory. Owing to the marked morphological heterogeneity of individual SC cases, dermatopathologists must be familiar with the different possible histopathologic manifestations of this neoplasm., (© 2020 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.)

First described in 1934, eccrine spiradenoma (ES) is a rare, benign adnexal tumour arising from eccrine sweat glands. It commonly presents as a slow-growing nodule on the upper trunk, and head and neck region, mostly in the age bracket of 15-35 years, with no gender preference. While no established guidelines exist for optimal management of malignant ES, some therapies have been studied. The diagnosis of this entity is extremely important as it can harbour a malignant component with disastrous outcomes which may be missed due to its strong resemblance to benign lesions, such as a papilloma. Here, we present the case of a 35-year-old lady who presented with a papilloma-like growth on the upper medial aspect of the thigh which was diagnosed as eccrine spiradenoma upon excision.

Mixed tumor of the skin (MTS) is a rare skin adnexal neoplasm occurring in sweat glands. It is usually benign, measures 0.5 to 3 cm, and presents as a slowly growing, painless, firm nodule commonly in the head and neck regions. Owing to its rarity and lack of distinctive clinical manifestations, confirmative diagnosis is made on the basis of its pathologic features. Malignant MTS also develops de novo or from preexisting benign MTS even though they occur rarely. It should be excised completely to exclude malignant potentials. Herein, we report a 35-year history of a giant MTS of eccrine type measuring approximately 10.5 × 6.5 cm on the right hemiface of a 91-year-old woman, which is the largest facial MTS reported in the literature so far, to the best of our knowledge.

Hidradenomas are benign sweat gland tumors that typically present as small nodules in adulthood. Their anatomic distribution is wide and rarely includes acral sites. In this setting, reliable separation from digital papillary adenocarcinoma is important, but notoriously difficult. Hematoxylin and eosin-stained sections of 25 hidradenomas on acral skin were retrieved. The clinical presenting features and morphologic findings were recorded, and follow-up was obtained. Immunohistochemistry was performed for AE1/3, CK5/6, EMA, CEA, SMA, S100, p40, and p63. The tumors presented as solitary nodules on the hands (n=17) and feet (n=8) of adults (age range: 20 to 81 y; median: 50 y), with an equal sex distribution. Histologically, the well-circumscribed tumors were lobular, with a solid and cystic growth within dermis. Duct and squamous differentiation and vascularized hyaline stroma were frequent. The majority (n=18) were poroid hidradenomas. Scattered cytologic atypia and mitotic activity (median: 2/10 HPF) were common, and a pseudoinfiltrative growth of strands in a hyaline to sclerotic matrix was noted in 5 tumors. No papillary structures, atypical mitoses, or tumor necrosis were present. Immunohistochemically, all tumors expressed AE1/3, CK5/6, p40, and p63 strongly and diffusely. Luminal differentiation was highlighted by epithelial membrane antigen and carcinoembryonic antigen staining. S100 and SMA staining was absent. Follow-up (1 to 288 mo; median: 61 mo), available for 20 patients, showed no local recurrences and no disease-related mortality. Acral hidradenomas and digital papillary adenocarcinomas share a well-circumscribed dermal growth pattern containing solid, cystic, and tubular areas with mitotic activity and at least focal cytologic atypia. Lack of papillary structures and the diffuse positivity for p40 and p63 in the absence of S100 and SMA expression are helpful features in favor of acral hidradenoma.

Background: The eccrine carcinoma is a rare form of skin adnexal malignancy, usually presenting as a locally invasive, solitary lesion in the head and neck region. Histopathologically and immunohistochemically, eccrine carcinomas are difficult to differentiate from cutaneous metastases of breast carcinomas. Unlike treatment of cutaneous metastasis, treatment of a solitary eccrine carcinoma entails excision, generally without systematic therapy., Case Description: A seventy-year-old woman previously treated definitively for (in situ) breast cancer, undergoes excision of a nodule on the scalp. The histopathology report indicates a lesion typical for cutaneous metastasis of breast carcinoma. However, diagnostic imaging excludes recurrent breast cancer or metastatic spread. When subsequent clonality testing with archived breast cancer tissue from the earlier episode does not show a relation, the pathologist defines the lesion as an eccrine carcinoma. A re-excision is conducted, which does not show any residual tumorous tissue, and at follow-up there are no signs of recurrence or metastases., Conclusion: As a relatively rare and unknown malignancy, with strong histopathological resemblance to cutaneous metastasis of breast carcinoma, eccrine carcinoma poses a diagnostic challenge to both clinicians and pathologists.

The authors present a case of an eyelid eccrine porocarcinoma, a very rare malignant sweat gland tumor characterized histopathologically by nests of atypical poromatous cells and the presence of duct-like lumina. Histopathologic analysis of this case also exhibited numerous loose tumor cells in the adjacent tear film, a finding that has not been previously described.

Solid carcinoma, probably the solid variant of microcystic adnexal carcinoma, is an apocrine adnexal tumor first described in 1998. The authors report an additional new case of the tumor at an unusual localization. A 78-year-old man presented with an asymptomatic firm plaque on his right thigh that had been present for 15 years. A biopsy was taken, and then, the lesion was removed. A pathological study showed a huge number of islands made up of aggregations of neoplastic epithelial cells. The epithelial islands showed variable sizes and shapes at scanning magnification, arranged columns, cords, and strands at the basis of the tumor. The neoplastic cells were embedded within a fibrotic stroma. Ductal differentiation, cystic structures, and neurotropism were also observed. Immunohistochemically, the neoplastic cells expressed high-molecular-weight keratin (cytokeratin 5/6), broad-spectrum keratin (AE1/AE3), p40, and p63. No immunoreactivity was found for BerEP4, cytokeratin 7, cytokeratin 19, cytokeratin 20, chromogranin A, carcinoembryonic antigen, and S-100. The lesion was completely removed with slow-Mohs micrographic surgery. Two stages and previous debulking were necessary to obtain free margins. The second stage included the muscular fascia. The patient remains free of tumor after a year of follow-up. Solid microcystic adnexal carcinoma is a rare skin tumor that seems to occur more frequently in the scalp than in the face, but no area of the body can be excluded, as reported in our case. Differential diagnosis should include sclerosing and clear-cell basal cell carcinoma, clear-cell dermal duct tumor, or desmoplastic trichoepithelioma. Mohs micrographic surgery is the treatment of choice.

Squamoid eccrine ductal carcinoma (SEDC) is an extremely rare cutaneous tumor of unknown etiology. We report the case of a 77-year-old man with a history of treated chronic lymphocytic leukemia along with numerous basal cell and squamous cell carcinomas who presented for evaluation of a 5-cm, stellate, sclerotic plaque on the left chest of approximately 2 years' duration and a suspicious 3-mm pink papule on the right nasal sidewall of 2 months' duration. Initial histology of both lesions revealed carcinoma with squamous and ductal differentiation that extended from the undersurface of the epidermis, favoring a diagnosis of SEDC. It was later determined that the patient had distant metastasis of SEDC. This report of an immunocompromised patient with SEDC is a rare case of distant metastasis of SEDC. A review of the literature on the diagnosis, treatment, and surveillance of SEDC also is provided.

Syringoid eccrine carcinoma is a rare malignant adnexal tumor that typically presents in the head and neck region. Involvement of the extremities is uncommon, with only a few cases reported in the literature. Here, we report our experience with a rare case of syringoid eccrine carcinoma occurring on the plantar surface of the right foot in a 47-year-old African American woman. Histologically, incisional biopsy revealed a tumor consisting of tubulocystic structures lined by basaloid cells with an infiltrative growth pattern, extending from the reticular dermis to the deep biopsy margin. Some of the nests and cords of basaloid cells displayed syringoma-like, tadpole morphology. Immunohistochemical analysis showed diffuse immunoreactivity with monoclonal carcinoembryonic antigen, epithelial membrane antigen, cytokeratin 7, S100 protein, and CD117. These morphologic and immunophenotypic features were most consistent with syringoid eccrine carcinoma. Syringoid eccrine carcinoma has a broad differential diagnosis which must be carefully ruled out by morphology, immunohistochemistry, and thorough metastatic survey with imaging studies. Our case highlights the importance of recognizing this rare entity, which is locally destructive and has a propensity for recurrence. To the best of our knowledge, this is the first reported case of syringoid eccrine carcinoma presenting on the sole of the foot.

Microcystic adnexal carcinoma (MAC) is a rare malignant cutaneous adenocarcinoma that typically occurs in the head and neck, particularly at the central face. There are only slightly more than 300 patients reported worldwide, and most patients occur in Caucasians. A 72-year-old man was referred to our hospital for definitive treatment of known MAC from previous biopsy. Wide excision of nasal tip and reconstruction of nasal defect with paramedian forehead flap and nasolabial flap transposition were performed rather than conventional Mohs surgery, due to grossly evident disease. Pathological examination verified 4.5 × 3 cm sized MAC with free resection margins. The patient is being followed up without any evidence of disease.

Adenomyoepithelioma (AME) is a biphasic neoplasm of epithelial and myoepithelial cells. It is most commonly found in the breast, although rare cases have been reported from the lung, salivary glands, and skin. There are 5 well-documented cases of cutaneous AME in the literature. We report a new case of cutaneous AME. Our case was commingled with apocrine hidrocystoma. This is the first report of cutaneous AME in a male patient and the first to describe SOX10 immunostaining in cutaneous AME. We review the literature on cutaneous AME and note the greater than chance colocalization with other adnexal tumors. We speculate that AME may represent localized overgrowth of myoepithelial cells within a pre-existent sweat gland tumor. Histopathologists should be aware of the potential of SOX10-positive myoepithelial neoplasms to mimic nodular melanocytic proliferations.

Malignant adnexal carcinomas of the skin are rare but associated with high propensity for local recurrence, and for some of the distinct subgroups they are known to metastasize regionally or distant. Biopsy is necessary for correct diagnosis, as the lesions cannot be separated from other tumour types entirely on their clinical appearance. The histologic diagnosis is troublesome, and the lesions are often mistaken for their benign counterpart, basal cell carcinoma or squamous cell carcinoma. The lesions are treated with surgery. Radiotherapy and chemotherapy may play a role in treatment, although the evidence is limited.

Background: Microcystic adnexal carcinomas (MACs) are slow-growing and often asymptomatic malignant skin tumours that usually develop on the facial skin and may reach considerable size. We present an uncommon case of MAC arising on the hair-bearing scalp and discuss our experiences and considerations., Case Report: A 58-year-old female was admitted with a histopathologically secured diagnosis of MAC of the temporal and occipital regions that had expanded to 10 × 12 cm. Magnetic resonance imaging revealed an infiltration of the skin and the subcutaneous adipose tissue. No lymphatic or haematogenic metastases were detected. Therapy consisted of resecting the tumour and reconstructing the area by applying an anterolateral thigh (ALT) flap. Histopathological evaluation revealed clear, 1-cm margins and a tumour-free periosteum. One-year postoperative follow-ups showed no evidence of recurrence, while the outcome was aesthetically pleasing., Conclusion: When screening for skin cancer, careful attention must be paid to the scalp. Resection of MAC with clear margins is mandatory to minimize the risk of recurrence. In this case, applying an ALT perforator flap to a large defect of the hair-bearing scalp led to a very satisfying result; it should be considered in comparable cases.

Introduction: Microcystic adnexal carcinoma (MAC) is a rare malignant cutaneous neoplasm presenting as a slow-growing, indurated nodule, papule or plaque. Clinically, the lesion can blend into the surrounding skin, obscuring borders and consequently delaying diagnosis histologically. Surgical and histologic techniques that emphasize examination of all margins may optimize management through early diagnosis and prevention of recurrences., Objective: This review aims to assess the current surgical and histology techniques that result in lower rates of tumor recurrence and, consequently, better clinical outcomes., Methods: A literature search of the PubMed database was conducted to identify studies examining wide local excision (WLE), Mohs micrographic surgery (MMS), radiotherapy (RT) and chemotherapy in the treatment of MAC., Results: WLE had a high likelihood of positive margins and local recurrence. MMS was found to have the lowest recurrence rates. Definitive RT could be considered for elderly patients or those who are poor surgical candidates, as large surgical defects may be required to obtain free margins with either WLE or MMS. Chemotherapy was found to be ineffective., Conclusion: Complete margin evaluation with MMS permits complete tumor removal with subsequently low recurrence rate.

We present the case of a 44-year-old female with an aggressive digital papillary adenocarcinoma of the right thumb. Aggressive digital papillary adenocarcinomas are rare tumours originating from sweat glands of the skin on the hand or foot. The tumour was located at the extensor side and had been excised in 2 operations after diagnosis as an eccine hidradenoma, which is exceptional in this case. The tumour was radically excised and the defect was reconstructed using arthrodesis, and a retrogradely perfused pedicle radialis fascial flap with skin graft, due to which amputation was avoided., (© Georg Thieme Verlag KG Stuttgart · New York.)

Background: Primary cutaneous cribriform carcinoma (PCCC) is a rare and under-recognized variant of sweat gland carcinoma, characterized by anastomosing tubules and solid nests producing a sieve-like appearance., Methods: Six cases of PCCC were clinically, histopathologically and immunophenotypically studied., Results: All cases showed an unencapsulated, nodular dermal tumor composed of solid and cribriform nests, cords and tubules embedded within a desmoplastic stroma. Some tubules showed micropapillary projections reminiscent of tubular adenoma, and intraluminal thin bridges resembling adenomatoid tumor. One case showed a predominantly solid component. Only two cases showed very focal decapitation secretion. Tumor cells expressed CK7, CK5/6, EMA, CEA, S-100, BerEP4 and c-kit and were negative for cytokeratin 20, estrogen receptor/progesterone receptor (ER/PR), androgen receptor and GCDFP-15. Calponin, p63 and smooth muscle actin (SMA) showed absence of a myoepithelial layer., Conclusions: Contrary to the original reports, our series shows that PCCC may be predominantly solid with only a minor cribriform component, and expresses c-kit and S-100 which may potentially lead to the misdiagnosis of adenoid cystic carcinoma. Immunohistochemical stains may aid in distinction from tubular adenoma. Current data suggest a favorable outcome, as metastatic disease has not been reported to date., (© 2015 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.)

Background: Eccrine poroma is a rare, benign skin appendage tumor originating from the intraepidermal portion of the eccrine sweat duct, which typically occurs on the sides and soles of the feet. Nonetheless, eccrine poroma may be found in any skin area bearing sweat glands., Objective: Herein we report a case of an eccrine poroma in an unusual location, the surgical management of the condition, and follow-up processes., (© 2014 Canadian Dermatology Association.)