Apocrine Papillary Hidrocystoma With Mucinous Metaplasia (Goblet Cell Type): A Case Report and Review of the Literature.

ABSTRACT: Mucinous metaplasia (goblet cell type) is exceptionally rare in the skin. This is the second case of apocrine papillary hidrocystoma with mucinous metaplasia (goblet cell type) and a review of the literature exploring the significance and frequency of mucinous metaplasia with goblet cells in nongenital skin. The patient is an elderly man who presented with a blue-pigmented nodule on the scalp that was clinically suggestive of an atypical nevus. Histologically, the lesion was composed of a simple cyst of cuboidal cells with decapitation secretion and mucinous metaplasia with goblet cells. Papillary formation was identified in the cysts. Most cases of cutaneous mucinous metaplasia have been reported on genital skin, usually after chronic inflammation of the area. This type of mucinous metaplasia is categorized as benign mucinous metaplasia of the genitalia (BMM) and is believed to be unrelated to apocrine glands owing to the different histologic features and absence of apocrine differentiation by immunohistochemistry. Mucinous metaplasia (goblet cell type) has been previously reported in benign adnexal tumors (eccrine acrospiroma/hidroadenoma, mixed tumor, and syringocystadenoma papilliferum) and in malignant tumors (apocrine hidradenocarcinoma and squamous cell carcinoma). To date, mucinous metaplasia has not been identified in the histologically normal apocrine glands.

Low-Grade Hidradenocarcinoma of the Foot With Metastasis to a Lymph Node.

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.

Reactive Eccrine Syringofibroadenoma (ESFA) in Association With a Merkel Cell Carcinoma Excision Scar.

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.

Reactive Eccrine Syringofibroadenomatosis Associated With Venous Leg Ulcers: A Case Report and Literature Review.

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.

Value of Immunohistochemistry to Differentiate Digital Papillary Adenocarcinoma From Acral Hidradenoma With Papillary Structures.

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.

MAML2 Gene Rearrangement Occurs in Nearly All Hidradenomas: A Reappraisal in a Series of 20 Cases.

ABSTRACT: Hidradenoma is a benign cutaneous adnexal neoplasm that occurs across a wide age range and at a variety of anatomic sites. Its most characteristic morphologic feature is the presence of diverse cell types including squamoid, clear, plasmacytoid, and mucinous cells. Hidradenoma is morphologically and molecularly similar to mucoepidermoid carcinoma, and both tumors are characterized by recurrent CRTC1-MAML2 cytogenetic translocations. Previous studies have suggested that approximately half of hidradenomas possess this translocation. This finding raised the question of whether translocation-negative hidradenomas might have an alternate molecular basis. Here, we sought to reevaluate the frequency of MAML2 translocation in hidradenoma in a series of 20 cases. We find that 90% show evidence of MAML2 translocation, suggesting that this genetic event is a nearly invariant feature of hidradenoma. These results inform our molecular understanding of this tumor and may be useful in challenging cases to distinguish hidradenoma from its histologic mimics.

Reappraisal of tubulopapillary hidradenoma-like tumor of the mandible: Suggested change in nomenclature to reflect tumor origin.

Several cases of intraosseous mandibular tumors have been reported under the name "tubulopapillary hidradenoma-like tumor of the mandible (TPHLTM)." However, the intraosseous occurrence of sweat gland tumors needs to be reappraised. The aim of this review was to propose a new name for these tumors to reflect the possible tumor origin. In view of the incidence and the tissue of origin, TPHLTM is more likely to be a salivary gland tumor than a sweat gland tumor. Among salivary gland tumors, a recently described salivary neoplasm called "sialadenoma papilliferum-like intraductal papillary tumor (SP-IPT)" seems to be histologically and genetically identical to tubulopapillary hidradenoma. Therefore, we proposed that the term TPHLTM be replaced by "SP-IPT of the mandible," which better explains its origin and could help in clarifying the nature of SP-IPT.

Association of HPV42 with digital papillary adenocarcinoma and the use of in situ hybridization for its distinction from acral hidradenoma and diagnosis at non-acral sites.

Digital papillary adenocarcinoma (DPAC) is a rare tumor of sweat gland origin that preferentially affects the digits and has the potential to metastasize. Its tumor diagnosis can be difficult. Well-differentiated variants of DPAC can be confused with a benign sweat gland tumor, in particular nodular hidradenoma. With the recent detection of HPV42 DNA in DPAC by next-generation sequence analysis, we reasoned that this association could be used for diagnostic purposes. To this end, we performed in situ hybridization for HPV42 on 10 tumors diagnosed as DPAC as well as 30 sweat gland tumors of various histology types, including 8 acral hidradenomas. All DPAC were positive for HPV42. Positive hybridization signals for HPV42 were seen in both primary and metastatic DPACs. All other tumors and normal tissues were negative. This study confirms the association of HPV42 with the tumor cells of DPAC through in situ hybridization. The positive test result in all lesions of DPAC and lack of detection of HPV42 in any of the acral hidradenomas or other sweat gland tumors examined in this series is encouraging for the potential diagnostic utility of the assay. As documented by two scrotal tumors of DPAC, the in situ hybridization test for HPV42 can also help support the rare occurrence of this tumor at a non-acral site.

Trichilemmal cysts with proteinaceous material: A potential diagnostic pitfall.

BACKGROUND: Cysts of the skin are observed frequently and their diagnoses are generally straightforward. However, atypical cystic lesions for which differentiation is indistinct have been noted. METHODS: We examined five cases of trichilemmal cyst with proteinaceous material (TCPM), which required differentiation from sweat duct/gland tumors. We investigated the histopathological findings of TCPMs and evaluated the immunohistochemical expression of cytokeratin (CK) 10, CK13, CK17, CK19, CD8, and CD117. Immunohistochemical analysis was performed on the 5 TCPMs, 10 trichilemmal cysts (TCs), 5 clear-cell hidradenomas, 5 poroid hidradenomas, and cutaneous normal adnexa. RESULTS: Apoptotic cells were present in the cyst wall with a small amount of keratin or calcification in the cavity of TCPMs. The TCPMs and TCs were negative for CK19 and CD117, on the other hand clear-cell hidradenoma and poroid hidradenoma were positive for CK19 and CD117. The restricted positivity for CK10 was detected in the suprabasal layers of the cyst walls of TCPMs and TCs. The immunostaining patterns of TCPMs and TCs were similar to those of normal follicular isthmus. CONCLUSIONS: The histopathological findings with characteristics of TCs and a panel of immunohistochemical antibodies including CD117, CK19, and CK10 contributed to a correct diagnosis of TCPM.

Late-onset eccrine syringofibroadenoma of the feet in a patient with hypohidrotic ectodermal dysplasia.

A 56-year-old woman with hypohidrotic ectodermal dysplasia presented with a 10-year history of persisting wart-like skin lesions on her feet. Biopsy revealed changes of eccrine syringofibroadenoma. These lesions are rare, with only nine case reports describing an association with ectodermal dysplasia of hidrotic type (Clouston and Schopf's syndrome). To our knowledge, this is the first case of eccrine syringofibroadenoma developing in the hypohidrotic/anhidrotic subtype of ectodermal dysplasia.

Hidradenocarcinoma: a rare but challenging diagnosis.

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.

Rapidly Enlarging Hidradenoma of the Eyelid.

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.

Tubulopapillary hidradenoma-like tumor of the mandible: Two case reports of an underrecognized entity.

Tubulopapillary hidradenoma-like tumor of the mandible is extremely rare, with only 3 cases published in the English-language literature. The clinicopathological characteristics and histogenesis of this tumor are unclear. Few pathologists and perhaps fewer clinicians are familiar with this entity, and it is likely underrecognized and under-reported. Herein, we present two additional cases, both misdiagnosed as malignancies preoperatively and postoperatively by different unwary pathologists. Awareness and knowledge of this enigmatic entity and its clinical and radiographic features, together with careful morphological assessment should enable the correct diagnosis and prevent unnecessary treatment.

Immunohistochemical Study of Non-Epithelial Cells in Spiradenoma.

BACKGROUND: Intratumoral lymphocytes are a defining feature of spiradenoma; however, there have only been a few reports on the phenotypic features of non-epithelial cells. Spiradenomas also contain numerous cells positive for S-100 protein and the nature of these cells is still controversial. METHODS: We performed a clinicopathological and immunohistochemical study of ten cases of spiradenoma. RESULTS: The study included seven men and three women. On histopathological examination, spiradenoma could be divided into two types: the vascular proliferating (VP) type (five cases) that featured granulation tissue with edema, vascular proliferation, and inflammatory cell infiltration into the stroma, and the common type (five cases), which did not include any of the aforementioned features. Immunohistochemical staining demonstrated a large number of cells positive for S-100 protein. These included cells with large pale nuclei, dendritic cells, and a few cells with small dark nuclei that were also positive for α-smooth muscle actin. Most of the cells infiltrating the parenchymata of these lesions were CD3-positive. The proportions of CD4-positive and CD8-positive cells were almost equal or CD8-positive cells were predominant. CD20+ cells were observed in five spiradenomas. In painful lesions, there were numerous nerve fibers near the tumor. CONCLUSIONS: In spiradenoma, CD3+ T cells were mainly seen in the parenchyma and CD8+ cells were predominant over CD4+ cells in most cases. CD20+ cells showed focal infiltration of the parenchyma and stroma, especially in VP-type lesions. S-100 protein-positive cells in spiradenoma contained not only Langerhans cells, but also cells with myoepithelial differentiation.

Histological findings and pathologic diagnosis of spiradenocarcinoma: A case series and review of the literature.

BACKGROUND: Atypical spiradenoma and spiradenocarcinoma present a diagnostic challenge. We aim to assess the significance of certain histologic features, which may facilitate diagnosis of these tumors. METHODS: A natural language search for cases of "atypical spiradenoma" and "spiradenocarcinoma" diagnosed between 2009 and 2018 was performed. Original slides were retrieved and a subset of cases (n = 5) were stained for Ki-67, p53, carcinoembryonic antigen (CEA), and S100. All cases (n = 7) were assessed for overall architecture, atypical mitotic figures, abnormal cytology, necrosis, ductal proliferation, dilated vessels, and loss of dual cell population. RESULTS: All our cases showed an abrupt transition from benign to malignant morphology, nuclear atypia, atypical mitotic figures, and a monomorphic loss of the dual cell population (7/7; 100%). The majority also had dilated vessels (6/7; 85.7%), and ductal dilation or proliferation (5/7; 71.4%). Fewer cases showed tumor encapsulation (3/7; 43%), massive necrosis (3/7; 43%), and focal cellular necrosis (1/7; 14%). All cases showed a relatively increased Ki-67 proliferation index at the transitional interface (5/5; 100%). Almost all cases stained positively for p53 (4/5; 80%). Malignant areas of tumor or at the transitional interface showed more intense S100 staining (3/5; 60%). All cases were negative for CEA. CONCLUSION: Histologic features that strongly favor atypical spiradenoma or spiradenocarcinoma include abrupt transition to malignant foci, atypical mitotic figures, and monomorphic loss of the dual cell population. Ki-67, p53, and S100 may help delineate areas of atypical or malignant transformation in spiradenomas.