WT1 expression in endocrine mucin-producing sweat gland carcinoma: a study of 13 cases

Local Cutaneous Scrotal Involvement of Paratesticular Mesothelioma

ABSTRACT

Paratesticular mesothelioma (malignant mesothelioma arising from the tunica vaginalis of the testis) represents a small proportion of mesothelial neoplasms, and cutaneous involvement by paratesticular mesothelioma is very rare. Cutaneous involvement can manifest as scrotal subcutaneous nodules from regional spread, distant metastasis, or direct extension through surgical scars. Mesothelioma has 3 histopathologic classifications that include epithelioid, biphasic, and sarcomatoid, which is rarely seen in paratesticular mesothelioma. Given the rarity of this condition, cutaneous mesothelioma may be misdiagnosed as histologic mimics, such as metastatic adenocarcinoma or adnexal neoplasms; thus, appropriate immunohistochemical workup and clinical correlation are required to make an accurate diagnosis. In this case, a 75-year-old man with a history of paratesticular mesothelioma, status postorchiectomy, presented with right-sided scrotal swelling, erythema, and subcutaneous nodules. These nodules were identified as local recurrence with cutaneous involvement by paratesticular mesothelioma on histopathologic examination. This case highlights the clinical and histopathologic features of this diagnosis and underscores the importance of dermatopathologists being aware of this condition to ensure accurate diagnosis.

Endocrine Mucin-Producing Sweat Gland Carcinoma: Case Presentation with a Comprehensive Review of the Literature

(1) Background: Endocrine Mucin-Producing Sweat Gland Carcinoma (EMPSGC) is a rare, low-grade, neuroendocrine-differentiated, cutaneous adnexal tumor, officially recognized by the World Health Organization (WHO) Skin Tumors Classification in 2018 as a separate entity and homologue of endocrine ductal carcinoma in situ (eDCIS)/solid papillary carcinoma of the breast. Although it is more frequent in the female sex, between 60 and 70 years old, in the peri-orbital region, EMPSGC has also been described in the male sex, in subjects under 60 and over 80, and in extra-eyelid localizations (cheek, temple, scalp), but also in extra-facial localizations (chest and scrotum). (2) Methods: We present the clinical case of a 71-year-old woman with an undated lesion of the scalp, which presented as a nodule, skin-colored, and 2.5 cm in maximum diameter. We also conduct a comprehensive literature review from 1997 to the end of 2022, consulting PubMed, Scopus, Web of Science (WoS), and Google Scholar using the following keywords: "Endocrine mucin-producing sweat gland carcinoma" and/or "EMPSGC" and/or "skin" and "cutaneous neoplasms". In addition, we followed the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines. A total of 253 patients were recorded; 146 were females (57.7%) and 107 were males (42.2%). The vast majority of the lesions were in the eyelids (peri-ocular region), and only a minority of cases involved the cheeks, supra-auricular, retro-auricular, and occipital region, with very rare cases in the scalp, to which the present is also added. (4) Conclusions: The morphological and immunophenotypical features are essential both for the correct diagnosis and to be able to classify this lesion among the corresponding eDCIS/solid papillary carcinoma of the breast, with neuroendocrine differentiation. Recent papers have attempted to shed light on the molecular features of EMPSGC, and much remains to be conducted in the attempt to subtype the molecular profiles of these entities. Future studies with large case series, and especially with molecular biology techniques, will be needed to further add information about EMPSGC and its relationship in the PCMC spectrum.

WT1 as a myoepithelial marker: a comparative study of breast, cutaneous, and salivary gland lesions

WT1 immunostain is expressed in various benign and malignant neoplasms, as well as normal myoepithelial cells. WT1 shows differential expression in non-neoplastic, benign, and malignant neoplastic myoepithelial cells of the salivary gland. In this study, WT1 immunostain and other myoepithelial markers were compared to investigate the value of WT1 as a myoepithelial marker, and to delineate the expression profile of WT1 in nonsalivary gland myoepithelial cells. WT1, p63, and calponin immunostains were performed on normal and lesional tissues from the breast (adenosis, sclerosing adenosis, lactating adenoma, nipple adenoma, tubular adenoma, adenomyoepithelioma, and adenoid cystic carcinoma [ACC]), skin (cutaneous mixed tumor, hidradenoma, spiradenoma, and ACC), and salivary gland (pleomorphic adenoma and ACC). The stained slides were digitized and orientated with H&E images and assessed simultaneously using QuPath. A total of 129, 58, and 56 breast, cutaneous, and salivary gland lesions, respectively, were included. There was poor agreement between WT1-p63 and WT1-calponin (κ < 0.1) in all organs, with absence of WT1 expression in normal salivary gland myoepithelium and most ACCs. There were no significant differences in WT1 expression in myoepithelial cells in normal breast tissue and benign breast neoplasms. Compared to pleomorphic adenomas, cutaneous mixed tumors showed lower WT1 expression (P < .001). WT1 is a less sensitive myoepithelial marker than calponin and p63. However, its unique pattern of expression in salivary gland primary for pleomorphic adenomas/cutaneous mixed tumor can favor a diagnosis of benign salivary gland tumors, particularly in small biopsy specimens.

Endocrine Mucin-Producing Sweat Gland Carcinoma: Emerging Evidence of Multicentric Cutaneous Origin and Occasional Concurrence With Analogous Breast Tumors

INTRODUCTION

Endocrine mucin-producing sweat gland carcinoma (EMPSGC) is a low-grade carcinoma with predilection for the eyelid. It is analogous to solid papillary carcinoma of the breast with both expressing neuroendocrine markers and the potential to progress to invasive mucinous carcinoma (IMC). Although over 80 cases of EMPSGC have been reported, few multicentric cases have been described in the literature. In this article, we report 9 cases of EMPSGC including 3 with multicentric disease.

METHODS

A computerized search was performed for EMPSGC and IMC of the eyelid from January 2000 to February 2021. Records were reviewed for age, sex, tumor location, and clinical impression.

RESULTS

Eight EMPSGC (7 associated with IMC) and 1 IMC of the eyelid were identified. Lesions were slightly more common in men (55%) than women. The mean age of presentation was 76 years (range, 59-98 years). Lesions ranged from 2.5 to 12 mm. Three cases had multicentric synchronous lesions on the skin. Histologically, these were well-circumscribed dermal tumors with solid or partially cystic nodules. Tested tumors expressed at least 1 neuroendocrine marker and were positive for CK7, ER/PR, 1 or more of GCDFP-15, mammaglobin, and GATA-3. One case had an associated IMC of the breast, and another case was associated with an intraductal papilloma of the breast in a man. There was no evidence of metastasis.

CONCLUSION

EMPSGC is a low-grade adnexal neoplasm, commonly affecting the eyelid of the elderly. Lesions often progress to IMC, metastases being exceptionally rare. EMPSGC can be bilateral and multicentric. Concurrence with breast neoplasms has been observed and deserves investigation.

Recent Advances on Immunohistochemistry and Molecular Biology for the Diagnosis of Adnexal Sweat Gland Tumors

Simple Summary

Cutaneous sweat gland tumors form an extremely diverse and heterogeneous group of neoplasms that show histological differentiation to the sweat apparatus. Due to their rarity, wide diagnostic range, and significant morphological overlap between entities, their accurate diagnosis remains challenging for pathologists. Until recently, little was known about the molecular pathogenesis of adnexal tumors. Recent findings have revealed a wide range of gene fusions and other oncogenic factors that can be used for diagnostic purposes and, for some, can be detected by immunohistochemistry. Among other organs containing exocrine glands, such as salivary glands, breasts, and bronchi, most of these biomarkers have been reported in homologous neoplasms that share morphological features with their cutaneous counterparts. This review aims to describe these recent molecular and immunohistochemical biomarkers in the field of sweat gland tumors.

Abstract

Cutaneous sweat gland tumors are a subset of adnexal neoplasms that derive or differentiate into the sweat apparatus. Their great diversity, rarity, and complex terminology make their pathological diagnosis challenging. Recent findings have revealed a wide spectrum of oncogenic drivers, several of which are of diagnostic interest for pathologists. Most of these molecular alterations are represented by gene fusions, which are shared with other homologous neoplasms occurring in organs containing exocrine glands, such as salivary and breast glands, which show similarities to the sweat apparatus. This review aims to provide a synthesis of the most recent immunohistochemical and molecular markers used for the diagnosis of sweat gland tumors and to highlight their relationship with similar tumors in other organs. It will cover adenoid cystic carcinoma (NFIB, MYB, and MYBL1 fusion), cutaneous mixed tumor (PLAG1 fusion), cylindroma and spiradenoma and their carcinomas thereof (NF-κB activation through CYLD inactivation or ALKP1 hotspot mutation), hidradenoma and hidradenocarcinoma (MAML2 fusion), myoepithelioma (EWSR1 and FUS fusion), poroma and porocarcinoma (YAP1, MAML2, and NUTM1 fusion), secretory carcinoma (ETV6, NTRK3 fusion), tubular adenoma and syringo-cystadenoma papilliferum (HRAS and BRAF activating mutations). Sweat gland tumors for which there are no known molecular abnormalities will also be briefly discussed, as well as potential future developments.

Endocrine Mucin-Producing Sweat Gland Carcinoma: A Systematic Review and Meta-Analysis

BACKGROUND

Endocrine Mucin-Producing Sweat Gland Carcinoma is a rare, under-reported cutaneous adnexal tumor that is often misdiagnosed and has an unknown incidence of metastasis.

OBJECTIVE

To determine the incidence of metastasis and tumor recurrence, as well as diagnostic accuracy and current trends in treatment modality.

METHODS

A search was performed following the Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines. Tumor pathology and clinical data concerning demographics, presentation, diagnosis, treatment and follow-up were assessed.

RESULTS

A total of 36 publications with 110 cases were identified. Initial pathological diagnosis was incorrect in 45.5% of cases. One case of metastatic disease was reported. The incidence of locoregional recurrence was 10.6% over a mean follow-up period of 21.3 months. Of cases with known methods of resection, 34.6% were resected by excisional biopsy, 42.8% were resected by wide surgical excision, and 31.3% were cleared by Mohs micrographic surgery.

LIMITATIONS

The low reported incidence and level of evidence was suboptimal with only case reports and retrospective case studies being reported.

CONCLUSION

Reported cases of this pathology demonstrate poor diagnostic accuracy. High rates of misdiagnosis and inadequate definitive treatment suggest the need for more comprehensive work-up and management of lesions suspicious for this pathology.

Current Diagnosis and Treatment Options for Cutaneous Adnexal Neoplasms with Apocrine and Eccrine Differentiation

Adnexal tumors of the skin are a rare group of benign and malignant neoplasms that exhibit morphological differentiation toward one or more of the adnexal epithelium types present in normal skin. Tumors deriving from apocrine or eccrine glands are highly heterogeneous and represent various histological entities. Macroscopic and dermatoscopic features of these tumors are unspecific; therefore, a specialized pathological examination is required to correctly diagnose patients. Limited treatment guidelines of adnexal tumor cases are available; thus, therapy is still challenging. Patients should be referred to high-volume skin cancer centers to receive an appropriate multidisciplinary treatment, affecting their outcome. The purpose of this review is to summarize currently available data on pathogenesis, diagnosis, and treatment approach for apocrine and eccrine tumors.

Endocrine mucin-producing sweat gland carcinoma and associated primary cutaneous mucinous carcinoma: Review of the literature

BACKGROUND

Endocrine mucin-producing sweat gland carcinoma (EMPSGC) is a rare, low-grade, cutaneous adnexal carcinoma with neuroendocrine differentiation. It is considered to be a precursor of invasive neuroendocrine type primary cutaneous mucinous carcinoma (PCMC).

OBJECTIVE

To review clinicopathological literature summary of EMPSGC and associated neuroendocrine PCMC from all reported cases and compare its behavior vs non-neuroendocrine PCMC data reported in the literature.

METHODS

A review of English literature of all EMPSGC cases with and without associated PCMC was carried out.

RESULTS

EMPSGC was associated with invasive neuroendocrine type PCMC in 35.7% of cases. We found the recurrence rate of PCMC associated with EMPSGC of about 12.3%, which is much less than the 30% recurrence rate reported for the non-neuroendocrine subtype of PCMC. The non-neuroendocrine subtype of PCMC shows a 4% and 11% rate of distant and lymph node metastasis, respectively, vs EMPSGC-associated neuroendocrine type of PCMC, which is very indolent and only one recent case of locoregional metastasis out of 190 EMPSGC cases has been reported so far.

LIMITATION

Limitation of our study includes data derivation from case reports and case series in the literature.

CONCLUSION

The prognostic benefits for this cohort of patients may be considered in their overall management.

Next Generation Sequencing analysis suggests varied multistep mutational pathogenesis for Endocrine Mucin Producing Sweat Gland Carcinoma with comments on INSM1 and MUC2 suggesting a conjunctival origin

Endocrine mucin-producing sweat gland carcinoma (EMPSGC) is a low-grade eyelid tumor. Small biopsies and insensitive immunohistochemistry predispose to misdiagnosis. We aimed to identify clarifying immunohistochemical and/or molecular markers. Clinicopathologic data (22 cases) was reviewed. Immunohistochemistry (Insulinoma-associated protein-1(INSM1), BCL-2, MUC2, MUC4, androgen-receptor, Beta-catenin, MCPyV) and next generation sequencing (MSK-IMPACT, 468 genes) was performed (3 cases). Female (n=15) and male (n=7) patients, mean-age 71.8 years (53-88), had eyelid/periorbital tumors (>90%) with mucin-containing solid/cystic neuroendocrine pathology. Immunohistochemistry (INSM1, BCL2, androgen-receptor, RB1, Beta-catenin) was diffusely-positive (5/5), MUC2 partial, MUC4 focal, and MCPyV negative. MSK-IMPACT identified 12 single-nucleotide-variants and one in-frame deletion in 3 cases, each with DNA damage response/repair (BRD4, PPP4R2, RTEL1) and tumor-suppressor pathway (BRD4, TP53, TSC1, LATS2) mutations. Microsatellite instability, copy number alterations, and structural alterations were absent. INSM1 and MUC2 are positive in EMPSGC. MUC2 positivity suggests conjunctival origin. Multistep pathogenesis involving DNA damage repair and tumor-suppressor pathways may be implicated.

An Update on Endocrine Mucin-producing Sweat Gland Carcinoma: Clinicopathologic Study of 63 Cases and Comparative Analysis

Endocrine mucin-producing sweat gland carcinoma (EMPSGC) is a rare, low-grade adnexal neoplasm with predilection for the periorbital skin of older women. Histologically and immunophenotypically, EMPSGC is analogous to another neoplasm with neuroendocrine differentiation, solid papillary carcinoma of the breast. Both lesions are spatially associated with neuroendocrine mucinous adenocarcinomas of the skin and breast, respectively. EMPSGC is ostensibly a precursor of neuroendocrine-type mucinous sweat gland adenocarcinoma (MSC), a lesion of uncertain prognosis. Non-neuroendocrine MSC has been deemed locally aggressive with metastatic potential, and previous works speculated that EMPSGC-associated (neuroendocrine-type) MSC had similar recurrence and metastatic potential with implications for patient follow-up. Only 96 cases of EMPSGC have been reported (12 cases in the largest case series). Herein, we present 63 cases diagnosed as "EMPSGC" in comparison with aggregated results from known published EMPSGC cases. We aim to clarify the clinicopathologic features and prognostic significance of the neuroendocrine differentiation of EMPSGC and its associated adenocarcinoma and to determine the nosological relevance of EMPSGC association in the spectrum of MSC histopathogenesis. Results established an overall female predominance (66.7%) and average presenting age of 64 years. EMPSGC lesions were associated with adjacent MSC in 33.3% of cases. The recurrence rate for neuroendocrine-type MSC was ~21%, less than the reported 30% for non-neuroendocrine MSC. There were no cases of metastasis. EMPSGC and neuroendocrine-type MSC are distinct entities with more indolent behavior than previously reported, supporting a favorable prognosis for patients.

Comparative performance of insulinoma-associated protein 1 (INSM1) and routine immunohistochemical markers of neuroendocrine differentiation in the diagnosis of endocrine mucin-producing sweat gland carcinoma

Endocrine mucin-producing sweat gland carcinoma (EMPSGC) is a rare cutaneous adnexal malignancy with predilection for the eyelids of older adults. It must be distinguished from metastatic adenocarcinomas of extracutaneous origin and from benign adnexal proliferations on partial samples when a solid growth component and mucin production are not evident. Thus, demonstration of neuroendocrine differentiation can help to ensure a correct diagnosis. Insulinoma-associated protein 1 (INSM1) is a novel neuroendocrine marker that has recently shown greater sensitivity than synaptophysin (SYN) and chromogranin (CHR) in the diagnosis of various neuroendocrine neoplasms. We compared the performance of these three markers across 10 examples of EMPSGC. All EMPSGCs expressed INSM1. Eight of ten were also immunoreactive for SYN; however, INSM1 staining was generally more intense and stained a greater proportion of the tumor cells. CHR staining was weak and focal in most cases. INSM1 staining was present in hidrocystoma-like components of cystic EMPSGC. These findings suggest that INSM1 may be more sensitive than SYN and CHR and thus valuable for establishing a diagnosis of EMPSGC.

Renal Cell Carcinoma Antigen Expression in Primary Cutaneous Endocrine Mucinous Carcinomas: A Case Series of 14 Patients and Review of the Literature

Endocrine mucin-producing sweat gland carcinoma (EMPSGC) and primary cutaneous mucinous carcinoma (PCMC) are both uncommon low-grade cutaneous adnexal tumors with predilection for the eyelids of elderly women. Their clinical appearance is nonspecific, typically presenting as a slowly growing poorly circumscribed papule, nodule, plaque, or swelling. Histological features of EMPSGC include a lobulated dermal neoplasm with bland cytology and an invasive mucinous component in up to half of the cases. PCMC exhibits tumor nests suspended in abundant pools of mucin with focal strands or nests of tumor cells infiltrating the dermis. Because of their rarity and banal cytological features, both entities pose a risk for misdiagnosis with other benign/malignant cutaneous adnexal neoplasms. Histomorphological features can suggest a diagnosis of EMPSGC or PCMC, but immunohistochemistry is necessary for confirmation. A review of the literature showed variable results of antigens present in EMPSGC, and many of the positive markers only show sparse or focal immunoreactivity of tumor cells. As a result, diffusely positive markers play a crucial role in identification of these tumors, particularly with initial superficial biopsies. We present 9 cases of EMPSGC and 5 cases of PCMC with strong and diffuse immunoreactivity to renal cell carcinoma antigen. This novel finding can be useful in the diagnosis of EMPSGC and PCMC in combination with other known positive markers to differentiate them from other cutaneous neoplasms. In addition, it provides further evidence that EMPSGC could be a precursor lesion to PCMC with both existing on a spectrum.

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

The group of malignant sweat gland neoplasms is characterized by a wide biologic spectrum, including tumors with indolent behavior, low-grade malignant potential with locally destructive tumor growth and high local recurrence rates and high-grade malignant potential characterized by risk for disseminated disease and disease-related mortality. Reliable diagnosis to predict behavior may be challenging for a number of reasons. The clinical presentation is often nonspecific. Many of the tumors are rare, and they are only infrequently encountered in routine diagnostic practice. A significant subset of tumors shows bland and innocuous histologic features. They are easily mistaken for benign tumors despite their potential for destructive growth and aggressive disease course. At the other end of the spectrum the tumors may resemble poorly differentiated carcinoma or adenocarcinoma and recognition relies entirely on sampling and carful histological examination. The tumors may be inseparable from cutaneous metastases from visceral primaries by morphology and immunohistochemistry, requiring careful clinical correlation and work-up. Conversely, cutaneous metastases are readily mistaken for cutaneous primary tumors. While the presence of a myoepithelial layer is a helpful feature in excluding metastatic deposits, it does not imply benign behavior of sweat gland tumors in general. The above issues and challenges are exemplified in the discussion of selected sweat gland carcinoma in this manuscript, with a focus on recently described entities and those with novel findings.

Endocrine mucin-producing sweat gland carcinoma of the eyelid: A clinical and histological conundrum

A 60-year-old male presented with a 6-month-old history of a left upper lid mass. The mass was excised, and histopathological evaluation showed a well-circumscribed, multinodular, intradermal tumor consisting of round-to-oval cells with round nuclei and mucin filled cysts. On immunohistochemical analysis, the tumor cells stained positively for cytokeratin (CK)-7, CK-8, estrogen receptor (ER), progesterone receptor (PR), mucicarmine, synaptophysin, gross cystic disease fluid protein-15 (GCDFP-15), and neuron-specific enolase (NSE). A diagnosis of endocrine mucin-producing sweat gland carcinoma (EMPSGC) of the eyelid was made and at 6-month follow-up, no recurrence was noted. In this communication, we discuss the pathology and treatment options of EMPSGC of the eyelid. Although an uncommon entity, EMPSGC may be considered as a differential when encountered with a suspicious, potentially malignant eyelid mass.

Endocrine mucin-producing sweat gland carcinoma: A study of 11 cases with molecular analysis

BACKGROUND

Endocrine mucin-producing sweat gland carcinoma (EMPSGC) is a rare, low-grade adnexal neoplasm that most commonly involves the eyelid. Analogous to solid papillary carcinoma of the breast, it probably represents a precursor lesion to mucinous carcinoma. Here, we describe 11 cases of EMPSGC with molecular analysis.

METHODS

We performed a retrospective search of the Johns Hopkins Medical Institute pathology database and identified 11 cases of EMPSGC. Immunohistochemistry was performed for chromogranin, synaptophysin, neuron specific enolase, estrogen receptor (ER), epithelial membrane antigen (EMA), cytokeratin 7 (CK7), and cytokeratin 20 (CK20). Array comparative genomic hybridization (aCGH) and BRAFV600E pyrosequencing were performed on two and three cases, respectively.

RESULTS

We observed a strong female predilection (73% females, 8/11 cases) with an average age of 66 years (range, 56-83 years). EMPSGCs were associated with adjacent benign sweat gland cysts (3/11), atypical intraductal proliferation (1/11), and mucinous carcinoma (1/11). Immunohistochemically, all tumors expressed at least one neuroendocrine marker, ER, EMA, and CK7, and were negative for CK20. aCGH demonstrated a 6p11.2 to 6q16.1 deletion (1/2 cases). All cases were negative for BRAFV600E mutation (3/3 cases).

CONCLUSION

This series provides further histopathologic support that EMPSGC represents a multistage progression to mucinous carcinoma. Additional studies are needed to understand its molecular mechanisms.

Endocrine mucin-producing sweat gland carcinoma: Clinicopathologic, immunohistochemical, and molecular analysis of 11 cases with emphasis on MYB immunoexpression

BACKGROUND

Endocrine mucin-producing sweat gland carcinoma (EMPSGC) is a rare low-grade primary cutaneous sweat gland carcinoma with predilection for the periorbital skin in elderly female patients.

METHODS

We describe 11 cases of EMPSGC using a broad panel of immunohistochemical markers including BerEP4, cytokeratin 7, CAM 5.2, synaptophysin, chromogranin, cytokeratin 20, Ki67, progesterone receptor, and estrogen receptor. Calponin (1A4) and p63 were used to detect surrounding myoepithelial cells. We also examined staining with a relatively new marker, MYB. Previous studies of MYB on EMPSGC remain limited. As mucin-rich basal cell carcinoma (BCC) represents a main differential diagnosis and primary cutaneous mucinous carcinoma (PCMC) could appear synchronous with EMPSGC, these lesions were also stained for MYB.

RESULTS

We found strong and homogenous nuclear MYB-expression in 10 EMPSGC cases stained for MYB. MYB staining was not performed in one case. Furthermore, PCMC and mucin-rich BCCs did not express MYB.

CONCLUSION

The strong nuclear MYB-positivity in EMPSGC could be useful as a new surrogate marker, especially in mucin-poor EMPSGC cases. Additionally, the staining of PCMC revealed absent MYB-expression leading to the conclusion that EMPSGC might not represent a precursor lesion for primary cutaneous mucinous carcinoma.

Mucinous Carcinoma with Neuroendocrine Differentiation of Salivary Gland Origin

Primary mucinous adenocarcinomas of the salivary gland are rare malignancies defined by aggregates of epithelial cells suspended in large pools of extracellular mucin. We report a case of a giant mucinous adenocarcinoma of salivary gland origin, with low-grade cytoarchitectural features and neuroendocrine differentiation arising in the submental region. Grossly, the tumor measured 12.5 × 13.4 × 8.2 cm and replaced the bone and soft tissues of the anterior oral cavity. Microscopically, the neoplasm was composed of large extracellular pools of mucin, which contained papillary and acinar aggregates, and small nodules of ductal type epithelium with minimal nuclear enlargement, powdery chromatin and little pleomorphism. The nodules comprised 20 % of the tumor and showed morphologic and immunohistochemical evidence of neuroendocrine differentiation. Examination revealed histologic features comparable to mammary gland analogues in mucin predominance, ductal type morphology, expression of estrogen and progesterone receptors, and GATA-3 positivity. This is the first case reported of mucin-rich carcinoma of salivary gland origin exhibiting neuroendocrine differentiation.

Endocrine mucin-producing sweat gland carcinoma: a study of three cases and CK8, CK18 and CD5/6 immunoexpression

Endocrine mucin-producing sweat gland carcinoma is a cutaneous adnexal tumor that is rarely reported in the literature. We identified only 29 previously reported cases. All these cases share some clinical morphologic and immunohistochemical features. Among the immunohistochemical markers, cytokeratins 5/6, 8 and 18 (CK5/6, CK8 and CK18) had not been previously studied in this tumor. Although studies with cytokeratin Cam5.2 exist, we know at present that this marker does not correspond to antibodies CK8/18, but rather to CK7 and CK8. We studied three examples of endocrine mucin-producing sweat gland carcinoma with 18 immunostains. Our cases showed an immunoprofile CK8+, CK18+, CK5/6- (or only focally positive), CK7+, GCDFP-15+ (2 cases), estrogen receptor+, progesterone receptor+, HER2-, neuron-specific enolase + (2 cases), anti-synaptophysin+, chromogranin A +, CD56 variable (1 case +, 1 case-), CD57-, anti-human D2-40- (two cases), p63- or focally positive, smooth muscle actin + with variable pattern of expression and smooth muscle myosin heavy chain expressed in a peripheral discontinuous layer in some nodules, but absent in most.