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Background: Adnexal tumors of the skin are rare neoplasms that encompass a wide range of dermatologic entities. Here, we investigated the pattern of adnexal tumors of the skin in the All African Leprosy and Tuberculosis Rehabilitation and Training Center (ALERT) hospital retrospectively., Methods: A hospital-based retrospective study was conducted at ALERT from histopathology records in the Armauer Hansen Research Institute (AHRI) pathology laboratory of patients diagnosed with any of the skin adnexal tumors during the time period January 2017 to December 2021. A structured data extraction sheet was used. Data entry was done using EpiData 4.6.0.6. Data were analyzed using SPSS version 25., Result: A total of 146 skin adnexal tumors were identified making the magnitude 2.8% of total biopsies. The 3rd decade of life was found to be the most common age group. Male-to-female ratio was 1 : 1.05. Majority of the tumors were benign (82.2%) and had sweat gland differentiation at 48.6%. Poroma (10.9%) was the most frequent tumor, whereas porocarcinoma (6.8%) made up the most frequent malignant tumor. The most common site was the head and neck region (48.6%). Only 21.2% of the tumors were correctly identified clinically., Conclusion: The magnitude of skin adnexal tumors is found to be slightly higher than other similar studies which could be because it was carried out in the largest dermatologic center in the country. The most common skin adnexal tumors identified, their localizations, and lines of differentiation are all in line with other studies. Histopathologic examination is mandatory for the accurate diagnosis of these tumors., (© 2024 the International Society of Dermatology.)

Poroma is a benign sweat gland tumour showing morphological features recapitulating the superficial portion of the eccrine sweat coil. A subset of poromas may transform into porocarcinoma, its malignant counterpart. Poroma and porocarcinoma are characterised by recurrent gene fusions involving YAP1, a transcriptional co-activator, which is controlled by the Hippo signalling pathway. The fusion genes frequently involve MAML2 and NUTM1, which are also rearranged in other cutaneous and extracutaneous neoplasms. We aimed to review the clinical, morphological and molecular features of this category of adnexal neoplasms with a special focus upon emerging differential diagnoses, and discuss how their systematic molecular characterisation may contribute to a standardisation of diagnosis, more accurate classification and, ultimately, refinement of their prognosis and therapeutic modalities., (© 2023 The Authors. Histopathology published by John Wiley & Sons Ltd.)

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.

Combined tumours are uncommon and therefore these tumours may pose a diagnostic challenge. In the current case report, it is aimed to present the clinicopathological features of a combined tumour including melanoma with aberrant cytokeratin expression and poroma., (© 2023 Australasian College of Dermatologists.)

Aims: Recently, YAP1 fusion genes have been demonstrated in eccrine poroma and porocarcinoma, and the diagnostic use of YAP1 immunohistochemistry has been highlighted in this setting. In other organs, loss of YAP1 expression can reflect YAP1 rearrangement or transcriptional repression, notably through RB1 inactivation. In this context, our objective was to re-evaluate the performance of YAP1 immunohistochemistry for the diagnosis of poroma and porocarcinoma., Methods and Results: The expression of the C-terminal part of the YAP1 protein was evaluated by immunohistochemistry in 543 cutaneous epithelial tumours, including 27 poromas, 14 porocarcinomas and 502 other cutaneous tumours. Tumours that showed a lack of expression of YAP1 were further investigated for Rb by immunohistochemistry and for fusion transcripts by real-time PCR (YAP1::MAML2 and YAP1::NUTM1). The absence of YAP1 expression was observed in 24 cases of poroma (89%), 10 porocarcinoma (72%), 162 Merkel cell carcinoma (98%), 14 squamous cell carcinoma (SCC) (15%), one trichoblastoma and one sebaceoma. Fusions of YAP1 were detected in only 16 cases of poroma (n = 66%), 10 porocarcinoma (71%) all lacking YAP1 expression, and in one sebaceoma. The loss of Rb expression was detected in all cases except one of YAP1-deficient SCC (n = 14), such tumours showing significant morphological overlap with porocarcinoma. In-vitro experiments in HaCat cells showed that RB1 knockdown resulted in repression of YAP1 protein expression., Conclusion: In addition to gene fusion, we report that transcriptional repression of YAP1 can be observed in skin tumours with RB1 inactivation, including MCC and a subset of SCC., (© 2023 The Authors. Histopathology published by John Wiley & Sons Ltd.)

Eccrine syringofibroadenoma (ESFA) is a rare adnexal tumor deriving from the acrosyringeal portion of the eccrine duct. Five subtypes of ESFA were described including a reactive form. Reactive ESFAs are associated with inflammatory and neoplastic dermatoses. In this article, we report the case of a 90-year-old woman presenting with 3 leg ulcers evolving for 2 years surrounded by large verrucous and eczematous lesions. Multiple skin biopsies showed anastomosing epithelial cords connected to the epidermis consistent with ESFA. We identified 8 cases of ESFA associated with chronic leg ulcers in the literature and reviewed their main clinical and histological features.

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.)

Background: Poroma is a benign, exclusively cutaneous, adnexal tumor with a predilection for palmoplantar skin., Objective: To analyze the clinical characteristics of poroma in our population., Material and Methods: Retrospective study of patients diagnosed with poroma between 2002 and 2021. We conducted a chart review to record age; sex; number, location, and diameter of lesions; time since onset; clinical characteristics; suspected clinical diagnosis; resection margin status; recurrences; and follow-up duration. Categorical variables were compared using the Fisher exact test. Continuous variables were compared using the t test or the Mann-Whitney U test depending on whether they were normally or nonnormally distributed., Results: We studied 80 patients (31 women and 49 men) with a median (interquartile range [IQR]) age of 65.5 (29) years. Median time since onset of poroma was 12 (21) months. Median lesion diameter was 8(7)mm, and none of the patients had multiple lesions. The lesions were located on the head and neck in 13 cases, the trunk in 13, the upper extremities in 11, and the lower extremities in 43. Twenty-three lesions (28.8%) were located at acral sites (5 on the palms and 18 on the soles). Women were more likely to have scalp lesions (P=.041). Acral lesions were more likely to be erythematous (P=.014). Five patients experienced local recurrence., Conclusions: Although poromas are particularly common in acral locations (especially the feet), most of the lesions in our series (71.3%) were located elsewhere. Acral lesions were more likely to show the classic clinical features of erythema and exophytic growth., (Copyright © 2022 AEDV. Publicado por Elsevier España, S.L.U. All rights reserved.)

Eccrine poroma is a benign adnexal neoplasm often mistaken for pyogenic granuloma, skin tag, squamous cell carcinoma, and other soft-tissue tumors. We describe a 69-year-old woman with a soft-tissue mass on the lateral aspect of her right hallux that was initially clinically diagnosed as a pyogenic granuloma. Histologic examination proved that this mass was instead an eccrine poroma, the rare benign sweat gland tumor. This case exemplifies the importance of a broad differential diagnosis, especially regarding soft-tissue masses of the lower extremity.

Primary cutaneous cribriform apocrine carcinoma (PCCAC) is an exceedingly rare sweat gland carcinoma. Clinically, it most often presents as a singular, asymptomatic nodule or cyst on the extremities of middle-aged patients and follows an indolent course. Both visceral and cutaneous cribriform tumors exist in nature. While a cribriform pattern is well recognized in tumors of visceral organs, there is a paucity in the literature on the defining characteristics for primary cutaneous tumors. Consensus regarding diagnostic criteria, etiology, and management protocols has yet to be achieved. We conducted an extensive literature review using pre-determined search criteria, resulting in 12 identified case reports and series on PCCAC that were subsequently analyzed. All data were compiled to provide a comprehensive update on the existing information regarding clinical presentation, histopathology, and management of reported PCCACs, as well as differential diagnosis, controversial issues, and recommendations for future considerations., (© 2022. This is a U.S. government work and not under copyright protection in the U.S.; foreign copyright protection may apply.)

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.)

Eccrine poroma (EP) is a rare benign adnexal tumor that may mimic benign or malignant tumors and differential diagnosis may be difficult under clinical and dermoscopic examination. Reflectance confocal microscopy (RCM) examination may add important information to diagnosis and subsequent management of solitary lesions for which dermoscopy can be challenging. The aim of the present study was to investigate features of EP at RCM in order to detect the characteristics that might aid in the differential diagnosis of EP versus other solitary lesions (benign or malignant). Secondary objective was to correlate the resulting features with histopathological findings. This monocentric retrospective observational case-control study included all EPs registered with RCM between January 2007 and May 2018. Control cases were benign or malignant lesions similar in clinical appearance, morphology, and dermoscopic features to EPs. RCM evaluators were blinded to clinical-dermoscopic images and to final histopathological diagnoses. Finally, RCM-histopathological correlation was performed. A total of 11 EPs and 33 controls were included in the present study. Among RCM parameters, "cords without palisading," "dark holes," "prominent vascularization" and "abundant stroma" resulted positively associated with EP in univariate analysis. RCM features correspond to the histopathological diagnosis of EP in 97% of cases, as illustrated by the cluster analysis. An excellent correlation between diagnostic features of conventional histopathology and RCM was observed. RCM assists in the differential diagnosis of solitary lesions, allowing to reach a correct diagnosis of EP through the identification of its four characteristics., (© 2022 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.)

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.)

Aims: Clear cells formed due to depositions of glycogen or lipids in the cytoplasm commonly occur in various tissues. Adipophilin (ADP), a lipid regulatory protein, is closely related to lipid droplets. This study aims to examine adipophilin expression in clear cells of various skin lesions., Methods: ADP expression was examined using immunohistochemistry in 108 sections from 15 skin lesion types with clear cell histology, namely, sebaceoma (n=16), sebaceous adenoma (n=3), sebaceous carcinoma (n=12), xanthomata cutis (n=10), xanthogranuloma (n=8), Paget's disease (n=10), Bowen disease (n=10), hidradenoma (n=9), atypical lipoma (n=5), superficial lipomatous nevus (n=5), metastatic renal cell carcinoma (n=5), squamous cell carcinoma (n=4), seborrheic keratosis (n=4), dermatofibroma (n=4) and clear cell sarcoma (n=3)., Results: ADP was not expressed in Bowen disease, hidradenoma or seborrheic keratosis. Four expression patterns, foamy, reticular, granular and punctate, were summarised based on their expression in clear cells. Different expression patterns were related to tissue origin and differentiation degree. Foamy expression was commonly observed in lesions with mature sebaceous glands and xanthomas; reticular expression in adipocytes; granular expression in xanthoma, xanthogranuloma and metastatic renal carcinoma and punctate expression in sebaceoma, sebaceous carcinoma, Paget's disease, squamous cell carcinoma and clear cell sarcoma. Furthermore, stronger staining with focal vesicular labelling was noted in sebaceoma than in sebaceous carcinoma. Characteristic labelling was noted, including the circular distribution in Touton giant cells of xanthogranulomas and focal distribution in the clear cells along the edge of necrotic tissue in clear cell sarcoma., Conclusions: ADP is useful in identifying intracytoplasmic lipids and can be used to diagnose skin lesions with clear cell histology, especially in some lesions with characteristic labelling., Competing Interests: Competing interests: None declared., (© Author(s) (or their employer(s)) 2022. No commercial re-use. See rights and permissions. Published by BMJ.)

Eccrine tumors are a rare cutaneous adnexal neoplasm originating from the sweat glands. The periungual region represents an uncommon localization for these neoplasms. We analyzed all published demographic, clinical, and treatment data on periungual eccrine tumors. A systematic review following PRISMA guidelines was performed of articles published prior to March 2021. Articles were included in the review if a full-text English version was available. Of the surveyed literature, 27 full-text case reports were included in the final analysis. Benign eccrine poroma and porocarcinoma were the most common tumor subtypes (nine and eight cases, respectively). Males were only affected by poroma and porocarcinoma, while females were affected by all tumor subtypes. The first toe was the most common lower extremity affected. Misdiagnosis led to delayed treatment in 25% of cases. As such, while periungual eccrine neoplasms are rare diagnoses, the nonspecific presentations of these growths raise concerns about misdiagnosis and delayed treatment. Further research is needed related to sex-differences in the epidemiology of these growths and into the prevalence of the first toe as a location. These tumors should be considered in the differential diagnosis for nail unit afflictions., (© 2021 the International Society of Dermatology.)

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.)

Endocrine mucin-producing sweat gland carcinoma is a low-grade eyelid tumor. Small biopsies and insensitive immunohistochemistry predispose to misdiagnosis. We aimed to identify clarifying immunohistochemical markers, molecular markers, or both. Clinicopathologic data (22 cases) were reviewed. Immunohistochemistry (insulinoma-associated protein 1, BCL-2, mucin 2 [MUC2], mucin 4, androgen receptor, β-catenin, and Merkel cell polyomavirus) and next-generation sequencing (Memorial Sloan Kettering integrated mutation profiling of actionable cancer targets, 468 genes) were performed (3 cases). Female patients (n = 15) and male patients (n = 7) (mean age 71.8 years; range 53-88 years) had eyelid or periorbital tumors (>90%) with mucin-containing solid or cystic neuroendocrine pathology. Immunohistochemistry (insulinoma-associated protein 1, BCL2, androgen receptor, retinoblastoma-associated protein 1, and β-catenin) was diffusely positive (5/5), MUC2 partial, mucin 4 focal, and Merkel cell polyomavirus negative. Memorial Sloan Kettering integrated mutation profiling of actionable cancer targets identified 12 single-nucleotide variants and 1 in-frame deletion in 3 cases, each with DNA damage response or repair (BRD4, PPP4R2, and RTEL1) and tumor-suppressor pathway (BRD4, TP53, TSC1, and LATS2) mutations. Microsatellite instability, copy number alterations, and structural alterations were absent. Insulinoma-associated protein 1 and MUC2 are positive in endocrine mucin-producing sweat gland carcinoma. MUC2 positivity suggests conjunctival origin. Multistep pathogenesis involving DNA damage repair and tumor-suppressor pathways may be implicated., Competing Interests: Conflicts of interest None disclosed., (Copyright © 2021 American Academy of Dermatology, Inc. Published by Elsevier Inc. All rights reserved.)

Rationale: Apocrine carcinoma is a rare malignant sweat gland tumor that has been reported in approximately 200 cases. This tumor usually occurs in the axilla, but in rare cases, it can also develop in the scalp. In the present work, we report 2 cases of cutaneous apocrine carcinoma of the scalp., Patient Concerns: Two men visited our outpatient clinic with recurrence of tumor after undergoing surgery for scalp tumor at another hospital., Diagnoses: Brain magnetic resonance imaging of a 56-year old man showed the presence of a 5.0 × 4.5 × 4.4 cm scalp mass in the right parietal region, invading the skull and dura mater and a 2.2 × 2.0 × 0.7 cm bony mass without any skin lesions right next to the scalp mass. Neck magnetic resonance imaging of a 76-year-old man revealed the presence of a well-defined oval mass in the subcutaneous layer of the left occipital scalp and 2 enlarged lymph nodes in the left neck. Definite diagnoses were made postoperatively. The patients were diagnosed with cutaneous apocrine carcinoma. The diagnosis was confirmed through histopathological and immunohistochemical staining tests., Interventions: The tumors were removed with a wide safety margin and reconstructive surgery was performed., Outcomes: Additional radiotherapy or chemotherapy was performed. Follow-up more than 6 months revealed no recurrence or metastasis., Lessons: If accurate diagnosis and treatment had taken place at the initial stages of the primary cutaneous apocrine carcinoma, it would have been possible to prevent recurrence and intracranial invasion. As recurrent primary cutaneous apocrine carcinoma can become aggressive and difficult to treat, even a small mass on the scalp must be evaluated carefully and treated properly., Competing Interests: The authors have no funding and conflicts of interest to disclose., (Copyright © 2022 the Author(s). Published by Wolters Kluwer Health, Inc.)

Abstract: Histopathologically both hidroacanthoma simplex (HS) and clonal seborrheic keratosis (CSK) are characterized by intraepidermal nests of tumor cells. Although they show subtle microscopic differences, they can be difficult to accurately differentiate. Previous immunohistochemical studies have been inconclusive. We conducted an immunohistochemical study with GATA3 and p63 on cases of HS and CSK tentatively identified by their microscopic appearances and cases of eccrine poroma and seborrheic keratosis as their respective controls. The clinical, histopathological, and dermoscopic findings of these cases were also reviewed. All cases of HS and poroma were negative for GATA3, whereas all cases of CSK and seborrheic keratosis were positive for GATA3. HS, CSK, and their controls were all positive for p63. Microscopic, clinical, and dermoscopic differences were also found between HS and CSK. Our study demonstrated that GATA3 is useful for differentiating HS from CSK. Our initial microscopic observations also proved to be reliable, but immunostaining with GATA3 is helpful for confirming the diagnosis or establishing the diagnosis of uncertain cases. Awareness of the clinical and dermoscopic features of these 2 entities could also avoid misdiagnosis based solely on pathological observation., Competing Interests: The authors declare no conflicts of interest., (Copyright © 2021 Wolters Kluwer Health, Inc. All rights reserved.)

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.)

Malignant adnexal neoplasms of the skin are a heterogeneous group of rare malignancies with eccrine, apocrine, sebaceous and follicular differentiation. Essential clinical practice recommendations for the overall management of these cancers are presented. Moreover, specific evidence-based findings according to diagnosis, therapy and follow-up of porocarcinoma, sebaceous carcinoma and microcystic adnexcarcinoma will be explained.

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.

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.)

BACKGROUND Primary cutaneous cribriform apocrine carcinoma is a histopathological variant of apocrine adenocarcinoma (AA) of the skin, which is a rare, low-grade malignancy. While low-grade in nature, cutaneous cribriform apocrine carcinoma can mimic a metastatic manifestation of a visceral or breast malignancy, and is important to distinguish as primary through clinical history, histology, and immunohistochemical studies, if indicated. CASE REPORT A 56-year-old man with past medical history remarkable for basal cell carcinoma and hypertension presented with a 12-month history of a slowly enlarging, asymptomatic nodule on his right anterior medial lower leg. Physical examination revealed a 12×9 mm indurated and erythematous nodule with no other masses or lymphadenopathy detected. Histology demonstrated a well-circumscribed proliferation of epithelial cells in fibrosing granulation tissue-like stroma having the delicate cross-bridging of a cribriform carcinoma. Immunohistochemical studies were significant for positive high-molecular-weight keratin and cytokeratin, focal positivity for carcinoembryonic antigen (CEA) and S100, with negative results for prostate-specific antigen (PSA) and cytokeratin 20. CONCLUSIONS Clinicians should maintain a high index of suspicion for metastasis when cutaneous cribriform apocrine carcinoma is diagnosed. The use of clinical history and appropriate laboratory workup with parameters such as age and sex can guide workup. After a wider excision with clear margins, follow-up for evidence of recurrence or metastasis is recommended, as the limited number of reported cases suggests that this assumption cannot be made with certainty.

Objectives: The diagnostic utility of En1 in the histopathologic differentiation of eccrine porocarcinoma (EPC) from invasive squamous cell carcinoma (SCC) was investigated., Methods: Expression of En1 and CK19 in 16 cases of EPC was immunohistochemically examined and compared with that in 32 cases of SCC., Results: In all 16 EPCs, En1 was expressed in 3% to 100% of tumor cells. In 20 of the 32 SCCs, En1 was expressed in 3% to 90% of tumor cells. A total of 13 of the 16 EPCs and five of the 32 SCCs were judged as En1 positive, with a cutoff value of 25%. In addition, 11 of the 16 EPCs and four of the 32 SCCs were CK19 positive. The frequencies of En1- and CK19-positive cases were significantly higher in EPCs than in SCCs. In a logistic regression analysis for predicting EPC, En1 and CK19 were independent markers. When expression patterns of En1 and CK19 were combined, none of the 32 SCCs was both positive. In contrast, 15 of the 16 EPCs were positive for either En1 or CK19., Conclusions: A combination of En1 and CK19 expression can improve the accuracy of histologic diagnosis of EPC., (© American Society for Clinical Pathology, 2020. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.)

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.

Aims: Laminin (Ln)-γ 2, one of the chains of Ln-332, is a marker of invasive tumours and is frequently expressed as a monomer in malignant tumours. Desmoplastic trichoepithelioma (DTE), some types of basal cell carcinoma (BCC) (infiltrating and morphoeic BCC) and microcystic adnexal carcinoma (MAC) belong to a group of tumours known as sclerosing adnexal neoplasms (SAN) that are frequently difficult to differentiate and often require immunohistochemistry for diagnosis. The aim of this study was to assess the usefulness of Ln-γ 2 expression in the differential diagnosis of DTE, infiltrating/morphoeic BCC, MAC and syringoma., Methods and Results: In this study, we compared the expression of Ln-γ 2 in infiltrating/morphoeic BCC (n = 28), DTE (n = 26), MAC (n = 10) and syringoma (n = 20). Immunohistochemically, Ln-γ 2 positivity was noted in 96% (27 cases) of infiltrating/morphoeic BCC and 90% (nine cases) of MAC, while all DTE and syringoma cases were negative. Furthermore, Ln-γ 2 expression pattern in infiltrating/morphoeic BCC was different from that in MAC. Ln-γ 2 expression was found in the cytoplasm of tumour cells in infiltrating/morphoeic BCC tumour cells, while in MAC linear expression was noted both along tumour nests and in the cytoplasm., Conclusion: Ln-γ 2 is a helpful adjunct in the differential diagnosis of SAN., (© 2019 John Wiley & Sons Ltd.)

Basaloid tumors of the skin pose a diagnostic challenge to pathologists, because the differential diagnosis is broad, sometimes with subtle differentiating features. We evaluated SOX10 expression in 120 primary cutaneous tumors with epidermal, sweat glandular, neuroendocrine/neuroectodermal, follicular, and sebaceous lineages. Our findings were compared with those of previous studies that evaluated SOX10 in tumors of the skin. SOX10 staining was seen in the majority of sweat gland tumors with the exception of syringoma and microcystic adnexal carcinoma. There were no immunoreactive cases among epidermal, neuroendocrine/neuroectodermal, follicular, or sebaceous tumors. These findings are comparable to reported in previous studies, and show SOX10 can be a useful adjunct in the differential diagnosis of nodular basaloid skin tumors. That marker has less utility in the assessment of sclerosing basaloid cutaneous neoplasms, because such tumors are almost uniformly nonreactive for it.