Do not break a sweat: avoiding pitfalls in the diagnosis of sweat gland tumors

Microcystic Adnexal Carcinoma (MAC) and Eccrine Cutaneous Mixed Tumor (ECMT): 2 Cases of Rare HPV-independent Vulvar Cutaneous Adnexal Tumors

Microcystic adnexal carcinoma (MAC) and eccrine cutaneous mixed tumor (ECMT) are both cutaneous adnexal tumors that may occur in the vulvar region, but are very rare at this site. Consequently, they may not enter the differential diagnosis of vulvar lesions for gynecologic pathologists in a subspecialized practice setting. Here we report a case of MAC and a case of ECMT recently diagnosed at our institution and underscore key histologic and immunophenotypic features of each lesion that can assist in their correct identification. Both MAC and ECMT have a tubular to corded pattern of lesional cells within a desmoplastic to chondromyxoid stroma. However, MAC shows true eccrine sweat duct differentiation, characterized by 2 SOX10 negative cell layers, including an outer p63+/p40+/EMA- basal cell layer and an inner p63-/p40-/EMA+ ductal layer. The main differential diagnostic considerations for vulvar MAC include other cutaneous adnexal tumors with true eccrine sweat duct differentiation, namely syringoma and squamoid eccrine ductal carcinoma (SEDC). Conversely, ECMT is characterized by a single SOX10+ cell population without immunoreactivity for p63 or p40. The main differential diagnostic considerations for ECMT include the apocrine variant of cutaneous mixed tumor (ACMT)-the cutaneous analog of salivary gland pleomorphic adenoma-and other SOX10+ salivary gland-type neoplasms. Unlike the recently described vulvar analog of HPV-associated multiphenotypic sinonasal carcinoma, neither MAC nor ECMT are HPV-associated and both are therefore p16 negative. In summary, we report one case each of vulvar MAC and ECMT and discuss the key histologic features and ancillary testing results that can help to differentiate these lesions from their morphologic mimics.

Hidradenocarcinoma of the Chest With Axillary Lymph Node Metastasis: Report of 2 Cases and Systematic Literature Review of a Breast Cancer Mimicker

ABSTRACT

Hidradenocarcinoma (HAC) is a rare malignant neoplasm originating from eccrine sweat glands, often presenting diagnostic challenges because of its resemblance to other malignancies, particularly breast cancer when occurring in the chest region. This report describes 2 cases of HAC with axillary lymph node metastasis, both initially misinterpreted clinically. The first case involved a 63-year-old woman with a sternal mass, near the right breast, initially suspected to be a sebaceous cyst. Histologic examination revealed a solid-cystic epithelial tumor with features suggestive of HAC, confirmed by immunohistochemical analysis. The second case concerned an 81-year-old woman with a subcutaneous growth in the sternal area, also diagnosed as HAC after histopathologic and immunohistochemical assessment. Both cases demonstrated strong estrogen receptor positivity, leading to the recommendation of hormonal therapy. A systematic review of the literature identified 21 similar cases of HAC in the chest wall, highlighting the diagnostic complexities and the potential for these tumors to mimic breast carcinoma. This review underscores the need for careful histologic and immunohistochemical evaluation to differentiate HAC from other malignancies, particularly in the breast region. Given the rare and the potential aggressive nature of HAC, early and accurate diagnosis is crucial for guiding appropriate therapeutic strategies and improving patient outcomes.

Encysted Tubular Sweat Gland Adenoma of the Nasal Ala: A Rare Cause for Unilateral Nasal Discharge

Benign cutaneous apocrine sweat gland adenomas in the nose are rare. We present the novel case of a nasal ala cutaneous sweat gland lesion. A 43-year-old male presents with a one year history of a right nostril mass with intermittent clear discharge, triggered by periods of hot weather and increased humidity. Histopathological analysis post-excision revealed a solid-cystic lesion of bi-layered ducts, with snouts suggestive of apocrine secretions. Given the close relationship of tumour enlargement with heat and expression of clear liquid upon direct pressure, we postulate that the intermittent tumescence represents sweat production and accumulation within the lesion. Laryngoscope, 135:602-604, 2025.

Endocrine Mucin-Producing Sweat Gland Carcinoma (EMPSGC) in a Dog: Immunohistochemical Characterization

A seven-year-old spayed female dog presented with multiple, small oval-shaped masses on the abdominal skin. The excised tissue was submitted for histopathological evaluation. Routine histology revealed basaloid nodules with stippled chromatin and pleomorphic nuclei. Morphologically, the tumor resembled a solid papillary carcinoma of the breast or an endocrine mucin-producing sweat gland carcinoma (EMPSGC). EMPSGC is a rare neuroendocrine-differentiated neoplasm. This study aimed to compare different immunohistochemical markers for distinguishing between canine sweat gland carcinoma (SGC) and mammary gland carcinoma (MGC). CK19 and Sox9 were useful in identifying SGC. Additionally, the tumor was positive for CK5, AE1/AE3+CK8/18, p63, vimentin, E-cadherin, and synaptophysin, while estrogen receptor staining was negative. The final diagnosis of canine EMPSGC was based on the tumor's morphological and neuroendocrine immunohistopathological features. Our report provides the first detailed description of a canine EMPSGC, an exceedingly rare tumor in dogs.

Squamoid Eccrine Ductal Carcinoma: An Unusual Diagnosis in a Pregnant Patient

Squamoid eccrine ductal carcinoma (SEDC) is an unusually rare neoplasm of the skin with a relatively high risk for local recurrence and a potential for metastasis. While typical presentations occur in older, male patients, this case report describes the diagnosis made in a pregnant patient in her third trimester. The clinical presentation, pathology, and treatment course of SEDC are outlined in this article.

Eccrine Ductal Carcinoma of the Eyelid

The authors present the third example of an eccrine ductal carcinoma of the eyelid. A woman in her early 70s presented with a lesion of the central right lower eyelid margin in the vicinity where an actinic keratosis was diagnosed by biopsy 2.75 years previously. Her dermatologist and ophthalmologist monitored the area of actinic keratosis, and it was stable for 2.5 years until the area became ulcerated and thickened with the loss of eyelashes. A wedge resection disclosed a squamous cell carcinoma in situ and a separate eccrine ductal carcinoma. The eccrine ductal carcinoma had in situ tumor thickening, an eccrine duct component, and an invasive tumor infiltrating the tarsal plate and replacing the normal meibomian glands. The invasive eccrine ductal carcinoma only mildly thickened the tarsal plate and was most likely an incidental finding in a biopsy prompted by the squamous cell carcinoma in situ. The 5-year relative survival rate for malignant apocrine-eccrine tumors is approximately 97%, and our patient is alive and without evidence of local or distant tumor recurrence 5.5 years following the excision of her eyelid tumor.

Whole-Exome Sequencing of a Case of Squamoid Eccrine Ductal Carcinoma Reveal Similarities With Cutaneous Squamous Cell Carcinoma

ABSTRACT

Squamoid eccrine ductal carcinoma (SEDC) is a poorly documented but likely underrecognized sweat gland malignancy with significant risk for local recurrence and potential for metastasis and rare disease-related mortality. Histopathologically, the tumor demonstrates a biphasic differentiation pattern: superficially, the tumor has squamous differentiation [indistinguishable from well-differentiated cutaneous squamous cell carcinoma (cSCC)], while the deeper aspect has a more infiltrative pattern with prominent ductal differentiation. Diagnosis of SEDC relies upon histopathologic examination alone. Its pathogenesis is poorly understood, and its genomic features have yet to be described. In this article, we characterize the genomic features in a case of SEDC through whole-exome sequencing, then compare its features with cSCC and other eccrine ductal carcinomas. Whole-exome sequencing revealed 30 mutations/Mb with 21 pathogenic or likely pathogenic mutations in total, identified across 14 different genes. The genomic abnormalities identified in this case of SEDC overlap considerably with those found in cSCC but not those of other sweat gland malignancies. The clinical and histopathologic features of SEDC previously reported and the genetic features determined from this case suggest that this tumor may arise initially as a well-differentiated cSCC that subsequently undergoes divergent differentiation focally to resemble a sweat gland malignancy. Genetic analyses of additional cases are warranted to clarify this consideration.

Axillary masses as clinical manifestations of male sweat gland carcinoma associated with extramammary Paget’s disease and accessory breast carcinoma: two cases report and literature review

Background

Male cases of accessory breast carcinoma and sweat gland carcinoma associated with extramammary Paget’s disease of the axilla are uncommon. In clinical diagnosis and treatment, it is necessary to determine the disease carefully and make a reasonable treatment strategy according to the patient’s situation.

Case presentation

We described two male cases of the special tumor with an axillary mass as the first clinical symptom, one of which was diagnosed as accessory breast cancer and the other as sweat gland cancer associated with extramammary Paget’s disease. We treated the two diseases individually in the hopes of providing a reference for the diagnosis and management of diseases with axillary nodules as the initial symptom.

Conclusions

The reports of these two cases can provide reference and corresponding thinking for clinical differentiation of axillary lymphadenopathy caused by different causes and subsequent treatment. These two cases may further enrich the database of rare cases and provide some ideas for the treatment of axillary lymphadenopathy caused by different causes.

TROP2 Expression in Sebaceous and Sweat Gland Carcinoma

Sebaceous carcinoma and sweat gland carcinoma (malignant tumors with apocrine and eccrine differentiation) are rare malignant skin adnexal tumors that differentiate toward sebaceous gland and eccrine and apocrine glands, respectively. Owing to the rarity of these carcinomas, standard treatments for advanced disease have not been established. Because the prognosis of patients with systemic metastasis is poor, a new treatment for these diseases is eagerly desired. Trophoblast cell surface antigen 2 (TROP2) and sacituzumab govitecan, an antibody–drug conjugate of TROP2, have attracted attention in the treatment of various solid tumors. In the current study, we immunohistochemically investigated TROP2 expression in 14 sebaceous carcinoma and 18 sweat gland carcinoma samples and found strong and relatively homogeneous TROP2 staining in both cancer types. The mean Histoscore, a semi-quantitative scoring ranging from 0 (negative) to 300, was 265.5 in sebaceous carcinoma and 260.0 in sweat gland carcinoma. These observations directly suggest that both sebaceous carcinoma and sweat gland carcinoma could be potentially treated with TROP2-targeted antibody–drug conjugates such as sacituzumab govitecan.

Breast carcinoma or sweat gland carcinoma? A report of two cases and a comparison with the literature

Primary apocrine carcinoma of the sweat gland is a neoplasm with a very low incidence that may represent a clinical and histological diagnostic challenge, as well as for adequate local, adjuvant, and advanced disease management. The average age of patients is around 67 years with no gender preference. This cancer develops primarily at the axillary and scalp levels and is clinically characterized by slow growth, but can progress aggressively with local, nodal, and metastatic involvement (primarily lung, liver, and bone). The recommended management, once the histology is established, consists of a wide local resection with a clear margin of 1 to 2 cm and regional lymphadenectomy if clinically positive nodes are detected. The adjuvant treatment (radiotherapy or chemotherapy) and for the advanced disease is not established. We report here the cases of two female patients initially diagnosed with breast cancer who were finally diagnosed with apocrine carcinoma of the sweat gland.

Primary Cutaneous Cribriform Apocrine Carcinoma

Patient: Male, 56-year-old

Final Diagnosis: Apocrine carcinoma

Symptoms: Lesion on skin

Medication: —

Clinical Procedure: —

Specialty: Dermatology