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Rationale: This article presents a challenging case involving an elderly male patient with a misdiagnosed intraductal mammary papilloma initially identified as a sweat adenoma through ultrasound imaging. The study aims to explore the histopathology, clinical presentations, and sonographic features of both conditions, emphasizing the contributing factors to the diagnostic misstep., Patient Concerns: A 61-year-old male reported a persistent left breast mass, along with pain and swelling, spanning a 6-month duration., Diagnoses: Ultrasound examination indicated a deep, square, mixed-echo mass in the left nipple, initially suggestive of a sweat adenoma. However, subsequent pathological analysis following resection under general anesthesia confirmed an intraductal papilloma., Intervention: The patient underwent surgical resection of the left breast mass under general anesthesia., Outcome: Post-surgery, the patient exhibited satisfactory recovery; however, regrettably, he was lost to follow-up., Lessons: This study underscores the challenge in differentiating between clear cell sweat adenoma and male intraductal mammary papilloma solely based on ultrasonic characteristics. It emphasizes the susceptibility of ultrasound-based diagnoses to misinterpretation, highlighting the critical need for a comprehensive pathological examination to establish a definitive diagnosis., Competing Interests: The authors have no funding and conflicts of interest to disclose., (Copyright © 2024 the Author(s). Published by Wolters Kluwer Health, Inc.)

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.)

Hidradenocarcinomas are rare cutaneous adnexal malignancies with sweat gland differentiation that can show a broad spectrum of histomorphologic appearances, ranging from low to high grade. The diagnosis of low-grade hidradenocarcinoma can be challenging and may be mistaken for benign hidradenomas, especially on superficial and partial samples. We performed a retrospective analysis of 16 low-grade hidradenocarcinomas, obtained from 4 large academic institutions. All neoplasms presented clinically as nodular lesions that ranged in size from 1.5 to 6.0 cm. All patients were adults and their age ranged from 33 to 74 years of age. All cases shared features similar to hidradenomas in the surface and mid portion of the tumors and all tumors had 1 or more histomorphologic clues to malignancy, including the presence of an asymmetric and infiltrative growth pattern (especially at the base of the tumors), perineurial invasion, and a desmoplastic stromal reaction. In the tumors evaluated for immunohistochemistry, the tumor cells were positive for p63, EMA, AE1/AE3, MNF116, and CK7. Three patients underwent sentinel lymph node biopsy, and 2 cases showed metastatic disease to regional lymph nodes. All cases (including the 2 cases that had regional lymph node metastasis), showed no local recurrence or distant metastasis observed after a complete re-excision of the tumors (follow-up range from 6 to 72 mo). Our study highlights the salient clinical and histopathologic features of low-grade hidradenocarcinomas and emphasizes the potential diagnostic pitfalls in distinguishing this entity from other neoplasms. Our results indicate that a combination of thorough histopathologic inspection is necessary to support the diagnosis of this rare neoplasm. These tumors can be exceedingly difficult to diagnose and awareness of the subtle features of low-grade hidradenocarcinoma is of importance are as it remains a diagnostic challenge for practicing pathologists., 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.)

Eccrine hidradenoma is a relatively rare benign tumor of sweat gland origin but with possible malignant transformation. It usually consists of solitary, well-demarcated papules or nodules covered with normal skin. Common sites of involvement are the scalp, face, limbs, and anterior trunk. Although the lining of the nasal vestibule includes hair follicles, sebaceous glands, and sweat glands, an eccrine hidradenoma originating in the nasal vestibule has yet to be reported. Herein, we describe a rare clinical presentation of nasal eccrine hidradenoma, treated successfully using a transnasal endoscopic approach.

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.)

Background: Eccrine spiradenocarcinoma (SC), also known as malignant eccrine spiradenoma, is a rare malignant cutaneous adnexal neoplasm arising from long-standing benign eccrine spiradenoma. Malignant skin tumors rarely show direct intracranial invasion. However, once the intracranial structure is infiltrated, curative excision with sufficient margins can become extremely difficult, particularly when the venous sinuses are involved. No effective adjuvant therapies have yet been established. Here, we report an extremely rare case of scalp eccrine SC with direct intracranial invasion, which does not appear to have been reported previously., Case Presentation: An 81-year-old woman presented with a large swelling on the parietal scalp 12 years after resection of spiradenoma from the same site. The tumor showed intracranial invasion with involvement of the superior sagittal sinus and repeated recurrences after four surgeries with preservation of the sinus. The histopathological diagnosis was eccrine SC. Adjuvant high-precision external beam radiotherapy (EBRT) proved effective after the third surgery, achieving remission of the residual tumor. The patient died 7 years after the first surgery for SC., Conclusions: Scalp SC with direct intracranial invasion is extremely rare. Radical resection with tumor-free margins is the mainstay of treatment, but the involvement of venous sinuses makes this unfeasible. High-precision EBRT in combination with maximal resection preserving the venous sinuses could be a treatment option for local tumor control., (© 2022. The Author(s).)

Eccrine acrospiroma is a benign tumor of skin and adnexa arising from eccrine sweat gland epithelium. It is usually solitary, slow growing tumor commonly affecting extremities. Rarely it affects head and neck region, and extremely rare in parotid region. Females are affected more often. Treatment of choice is wide local excision with adequate skin margins. Although benign this tumor is very notorious for recurrence after inadequate resection. We describe here a case of young male patient with recurrent eccrine acrospiroma over parotid region which was managed by wide local excision with primary repair with excellent results.

Hidradenocarcinoma is a rare, aggressive cancer arising from sweat glands. Hidradenocarcinoma has no definitive histologic features compared to its benign hidradenoma, thereby posing a diagnostic challenge for clinicians and pathologists. This novel case report demonstrates specific MRI signs that suggested malignant degeneration of hidradenoma., (Copyright © 2021 Elsevier Inc. All rights reserved.)

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.

Hidradenoma is a rare benign neoplasm, with few cases reported to involve the eyelid. When affecting the eyelid, hidradenomas may mimic other benign or malignant lesions. Rarely, a benign hidradenoma may transform into a malignant hidradenoma and metastasize. The authors present a case of a benign hidradenoma arising from the eyelid, presenting with rapid growth, ulceration, and bleeding, suggestive of a malignant lesion., Competing Interests: The authors have no financial or conflicts of interest to disclose., (Copyright © 2021 The American Society of Ophthalmic Plastic and Reconstructive Surgery, Inc.)

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.

Hidradenocarcinoma is a rare neoplasm of the eccrine cells of the sweat glands, usually asymptomatic with slow growing and higher incidence between 50 and 80 years, occurring in both sexes and preferentially located in the palmar, plantar, frontal, axillary and nuchal regions. It has an aggressive behavior, with high rate of local recurrence and distance metastasis, associated with a poor prognosis. We present a case of hidradenocarcinoma of the scrotum manifested by lymph node metastasis through an exercise of clinical and histological differential diagnosis of an inguinal adenopathy in a young adult.

Hidradenomas are tumours that arise from the adnexal structures, both eccrine and apocrine and are histologically benign. The tumours that arise from eccrine differentiation are known as poroid hidradenomas and when they arise from the apocrine glands they are called nodular hidradenomas. In our centre a 13-year-old boy presented with a slow-growing, painless erythematous fungating nodule on the left upper arm over a period of 18 months at the site of the BCG vaccination. The nodule was surgically excised and sent for histopathological examination, leading to a diagnosis of nodular hidradenoma. This case is presented to highlight its rarity, together with its clinical features that were suggestive of malignancy but proved ultimately to be benign., (© 2016 The Australasian College of Dermatologists.)

Clear cell hidradenoma is a rare skin tumor in the head and neck. Clear cell hidradenoma of skin is an uncommon soft tissue tumor originating from the sweat glands. The authors report a case of clear cell hidradenoma developing in the chin in a 61-year-old woman, which occurred during the course of 8 months. The clinical and histologic findings of the tumor are documented. The lesion was totally removed by excision and revealed no evidence of recurrence.

Background: Malignant acrospiroma is a rare tumor of the eccrine sweat glands accounting for around 6% of all malignant eccrine tumors. Typically, it presents as large ulcerated nodules, and diagnosis can be challenging as it has great overlap with its benign counterpart., Case Presentation: We herein report a case of acral malignant acrospiroma, initially treated with surgical excision and adjuvant radiotherapy. After metastatic disease was confirmed, subject received multiple lines of chemo- as well as targeted therapy. Genomic testing was also done using next generation sequencing., Conclusion: To the best of our knowledge, this is the first case of acral malignant acrospiroma with reported next generation sequencing results.

Introduction: Malignant eccrine spiradenoma is a rare and aggressive tumor, developed on the epithelium of eccrine sweat glands. Typically, it occurs after malignant transformation of benign eccrine spiradenoma, but sometimes it happens de novo., Observation: We report a case of malignant eccrine spiradenoma in a 62-year-old woman. The patient presented a rapid increase in size of a long-standing tumoral lesion of her forearm. There was no secondary lesion on the chest, abdomen or pelvis at the CT-scanner. Cutaneous biopsy of the lesion was performed and showed a carcinoma with no contact with epidermis. On this biopsy, we could not affirm if the tumor was a metastatic process or a primary tumor of the skin. Histologic examination of the surgical removal of the tumor showed an undifferentiated carcinoma with adjacent nodules of eccrine spiradenoma. Immunohistochemical assessment of Ki67 expression showed a weak expression (5%) in the benign spiradenoma nodules and a high rate expression (80%) in the malignant neoplasm. The final diagnosis was an undifferentiated carcinoma arising from preexisting benign spiradenoma., Discussion: Malignant eccrine spiradenoma is not frequent and is rarely described in the international literature that may lead to diagnostic difficulties., (Copyright © 2016 Elsevier Masson SAS. All rights reserved.)

Hidradenoma papilliferum (HP) is a benign epithelial tumor most commonly seen in the vulva. It is proposed to be derived from the anogenital mammary-like glands and is histologically very similar to the mammary intraductal papilloma (IP). Approximately 60% of mammary IPs have activating mutations in either PIK3CA or AKT1, with each gene accounting for 30% of cases. In this study, we screened the mutation statuses of PIK3CA, AKT1, RAS, and BRAF in 30 HPs. The results showed that activating mutations in either PIK3CA or AKT1 were identified in 20 tumors (67%); 19 tumors had PIK3CA mutations (63%; 13 in exon 20 and 6 in exon 9), and 1 had an AKT1 E17K mutation (3%). BRAF V600E mutation was found in an HP that also had a PIK3CA H1047R mutation. No RAS mutation was found. The mutation status was not correlated with the degree of epithelial cell hyperplasia. We conclude that although there might be site-related variations in the mutation frequencies of PIK3CA and AKT1 genes, HP is histologically and also genetically very similar to the mammary IP, suggesting that HP can be viewed as the extramammary counterpart of mammary IP., (Copyright © 2016 Elsevier Inc. All rights reserved.)

Background: Malignant sweat gland adnexal tumors are rare with an incidence of 0.001%. Of these, clear cell hidradenocarcinoma is an extremely uncommon subtype that accounts for 6% of malignant eccrine sweat gland tumors. They occur commonly in the head, neck, and extremities. Although they have a propensity for local recurrence, intracranial extension with brain invasion is extremely rare., Case Description: We report a 76-year-old man with a large, recurring, ulcerated, fungating scalp swelling of 14 years who presented with focal seizures and drowsiness. Neuroimaging revealed a massive tumor arising from the scalp to invade the left parietal lobe and extending to the right side with occlusion of the superior sagittal sinus. The overlying parietal bone was lytic with a "moth-eaten" appearance. He underwent wide excision of the scalp lesion, near-total cerebral tumor decompression followed by titanium mesh cranioplasty, rotation flap reconstruction of the scalp, and adjuvant radiotherapy to the skull vault. Histopathology revealed clear cell hidradenocarcinoma. Whole-body positron emission tomography scan did not reveal any other lesion. At 24 months' follow-up, he remains recurrence free., Conclusion: We report a rare indolent case of clear cell hidradenocarcinoma invading the brain, which was managed with near-total decompression and adjuvant radiotherapy. Intracranial extension in such aggressive tumors poses challenges in management, and regular neuroimaging surveillance is advised., (Copyright © 2016 Elsevier Inc. All rights reserved.)

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.)

The progressive calcification and fragmentation of elastic fibers, primarily affecting the skin, are histopathologic features typically associated with pseudoxanthoma elasticum (PXE), pseudo-pseudo PXE, or even acquired PXE. We present a case of a 65-year-old woman, with a known history of breast carcinoma, status after wide excision (T1N0Mx) in 2010, who presented with a 0.6 × 0.5-cm, nontender pink nodule in the right inferior axilla of 1 week duration on the same side as her mastectomy. Histopathologically, the lesion revealed a circumscribed, nonencapsulated bland dermal tumor with poroid and clear cells and foci of ductal differentiation-features diagnostic for hidradenoma. Of note, immediately adjacent to the hidradenoma, the specimen also exhibited short, frayed elastic tissue fibers (positive for EVG and Von Kossa stains)-features reminiscent of PXE. With this case, we expand the spectrum of reaction patterns observed in the skin to include a PXE-like change, a reaction pattern that, to the best of our knowledge, has not been previously reported in association with a benign cutaneous tumor.

Background: Hidradenocarcinoma (HAC) is a rare malignant adnexal neoplasm with reported metastatic potential and undefined optimal treatment., Objective: To review clinical characteristics and outcomes of patients with HAC treated with Mohs micrographic surgery (MMS)., Materials and Methods: The authors performed a retrospective chart review of patients with HAC treated by MMS at Mayo Clinic from 1993 to 2013, recording patient demographics, tumor characteristics, MMS stages to clearance, follow-up, recurrence, metastasis, and mortality., Results: Ten patients underwent MMS for HAC more than 20 years. The average age was 62.8 years, with 6 females and 4 males. Occipital scalp was the most common location (40%), followed by extremities (30%) and face (20%). In 5 of 7 cases (71%), "cyst" was the working clinical diagnosis. The average preoperative lesion area was 3.18 cm, with an average of 1.5 MMS stages required for clearance. Mean postoperative follow-up was 7 years (range, 5-205 months). No tumors treated with MMS recurred, metastasized, or led to disease-related mortality., Conclusion: Mohs micrographic surgery seems to be a useful treatment modality for HAC. This is the largest reported series of HAC treated with MMS with long-term follow-up.

A 46-year-old woman was evaluated for a "recurring papilloma" of the left medial upper eyelid margin. Beneath the papillary lesion medial to the punctum was a 5-mm diameter cutaneous mass thought to be cystic. After excisional biopsy, histopathologic analysis documented the presence of an epidermal keratinizing squamous papilloma surmounting a circumscribed dermal papillary hidradenoma composed of deeply eosinophilic columnar cells. Additionally, there was intraductal proliferation of tumor extending toward a subclinical poral opening through the epidermis. Immunohistochemistry proved the apocrine nature of the benign, non-cystic lesion by virtue of its nuclear androgen receptor and cytoplasmic gross-cystic disease fluid protein-15 positivity, along with its smooth muscle actin-positive myoepithelial layer. This and prior cases establish that apocrine tumors, both benign and malignant, are strictly localized at or near the eyelid margin where only apocrine glands are found. These tumors are more often papillary than solid adenomas, and most exceptionally can be malignant. We review the differential diagnosis of simulating eccrine eyelid tumors. We recommend wide local excision for benign lesions, in view of possible intraductal extension that can be eccentric to the main tumor and the miniscule potential for malignant transformation., (Copyright © 2014 Elsevier Inc. All rights reserved.)

An 84-year-old man presented with a tumor of the right caruncle causing epiphora due to insufficient eyelid closure. The tumor was cystic and mucinous in appearance. MRI showed a solitary tumor of the caruncle with no adhesions to neighboring tissue. The mass was removed by carunculectomy. Histopathologic examination revealed a tumor composed of epithelial cells with intervening strands of hyalinized stroma. Solid areas were predominant but a cribriform area could also be distinguished. Periodic acid-Schiff positive, diastase-labile material (glycogen) was detected in many tumor cells. Immunohistochemical staining of the tumor cells demonstrated positive staining with antibodies against CK-CAM 5.2, BER-EP4, p63, and smooth muscle actin-positive cells in some areas. The tumor was diagnosed as a nodular hidradenoma of the caruncle, which has never been reported before and should be included in the diagnoses of caruncular tumors.

Introduction: Persistent genital arousal disorder (PGAD) is an intrusive and unremitting disorder for which several possible etiologies and treatments have been suggested., Aim: To describe a woman who developed PGAD in association with a periclitoral mass, a potential physical cause of the disorder that has not been previously described in the medical literature., Methods: A postmenopausal woman presented with 6 months of persistent, unrelenting genital arousal and clitoral pain that was unrelated to sexual stimuli. Careful examination revealed a tender, firm, mobile, left-sided mass that appeared to compress the dorsal nerve of the clitoris., Results: Complete excision of the mass resulted in full resolution of her symptoms over several weeks., Conclusion: Localized causes of persistent genital arousal, though rare, should be included in the differential diagnosis PGAD as detection and treatment can lead to a complete recovery., (© 2013 International Society for Sexual Medicine.)

Hidradenocarcinomas are rare, yet highly malignant tumors of eccrine sweat gland origin. Due to its locally aggressive growth and likelihood for metastasis it should be considered as a differential diagnosis especially in case of suspicious intraoperative findings. We report the case of a 73-year-old female patient presenting with a hidradenocarcinoma of the wrist. Treatment of hidradenocarcinomas is similar to the treatment of sarcomas: The first step is an incisional biopsy and obtaining an expert second opinion on the histopathological diagnosis as well as staging. The second step is a clear margin resection of the tumor and the plastic-surgical reconstruction. A long-term follow-up is mandatory to detect potential recurrence or metastasis., (© Georg Thieme Verlag KG Stuttgart · New York.)

Hidradenomas are adenomatous tumors of sweat gland origin that are usually benign and can occur in any cutaneous skin surface. When malignant, the tumors have high recurrence rates and are often fatal. Because of their infrequency and clinical ambiguity, hidradenomas are often misdiagnosed as other soft-tissue masses. Radiation and chemotherapy have not shown to be of benefit; therefore, wide aggressive excision and lymphadenectomy are currently the treatments of choice. We present the case of a patient with a malignant hidradenoma presenting in her medial heel. After excisional biopsy identified the tumor, the patient was successfully treated with wide excision and delayed closure via vacuum-assisted closure.

Clear cell hidradenocarcinomas are extremely rare neoplasms, with very few well-documented cases reported in the literature. The most common sites are the head and neck regions. These tumors are histologically malignant but are not always aggressive. They are known for recurrence and may metastasize widely. Treatment is wide local resection. We report on a case of clear cell hidradenocarcinoma occurring over the eyelid together with a review of the literature.

Hidradenocarcinoma is a rare adnexal neoplasm representing the malignant counterpart of hidradenoma derived from eccrine sweat glands. Misdiagnosis of this disease is common due to the wide variety of histological patterns and rarity of this malignancy. We report an 87-year-old man presenting with a rare case of biopsy-proven hidradenocarcinoma of the finger. There is no standard care of treatment of hidradenocarcinoma, especially of those tumors in rare locations such as the fingers, given its rarity, variable tumor behavior and histology. Although limited treatment strategies exist, detailed data including TNM, location, histologic type and grade, and patient age should be gathered for optimal treatment strategy. The literature supports a 3-fold approach to these malignancies involving margin-free resection, sentinel lymph node biopsy to evaluate possible metastasis, and long-term follow-up given high risk of recurrence. Our treatment strategy involved a 4-fold, multidisciplinary approach involving reconstruction to optimize tumor-free remission and hand function.

Purpose: Hidradenoma papilliferum (HP) is a cystic lesion of apocrine gland origin that occurs most commonly in the perineal region. Although there are scattered reports of HP involving the eyelid, to our knowledge, we present the first case of HP of the orbit., Methods: A 63 year-old female presented with progressive left upper eyelid fullness over an 18 month period., Results: The lesion was excised via transconjunctival anterior orbitotomy without incident., Conclusions: The pathologic features of HP are presented.

Exceedingly rare cases of neoplasms with clear-cut histopathologic features of benignity can show locoregional or even distant spread. Such cases can become putative examples of "benign metastasis" when a completely favorable clinical outcome is documented after an adequately long follow-up. We report 8 cases of morphologically benign clear cell nodular hidradenoma (CCNH) with lymphatic involvement. In 5 cases the cutaneous tumor showed small foci of intravascular deposits of neoplastic cells; in 2 cases the cutaneous tumor presented with a synchronous tumor in a regional node; in 1 case a nodal location CCNH was found with no evidence of any primary in the skin. All the cases were treated with conservative surgery and none of them showed disease progression during a follow-up period ranging from 2 to 11 years. These data suggest that in the absence of other histopathologic features of malignancy, lymphatic spread in CCNH can still carry an excellent prognosis and can be therefore considered as an example of "benign metastasis." As the latter concept can be set forth only after an uneventful long-term follow-up, in routine practice, cases of morphologically benign CCNH with lymphatic involvement are best labeled "atypical CCNH," or "CCNH-like tumor of uncertain malignant potential."

The authors present a case of seemingly textbook digital osteomyelitis with draining ulceration. Per protocol, specimens were sent to pathology with the intent to verify and identify the offending organisms. Surprisingly, the textbook osteomyelitis returned with a pathological diagnosis of rare sweat gland tumor, malignant eccrine acropsiroma, prompting immediate systemic medical workup and treatment. This case emphasizes the importance of proper laboratory workup of all surgically removed specimens, despite having a "typical" presentation.