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

Recurrent GATA3 P409Afs*99 Frameshift Extension Mutations in Sweat-gland Carcinoma With Neuroendocrine Differentiation

Sweat-gland carcinoma with neuroendocrine differentiation (SCAND) was recently proposed as a new cutaneous adnexal neoplasm with neuroendocrine differentiation; however, its genetics are not well known. Herein, we performed clinicopathologic and genetic analyses of 13 SCAND cases and 5 control cases of endocrine mucin-producing sweat gland carcinoma (EMPSGC). The SCAND group included 11 males and 2 females with a median age of 68 years (range, 50 to 80 y). All SCAND lesions occurred in the ventral trunk or genital area. Of the 13 SCAND cases, 9 and 5 exhibited lymph node and distant metastases, respectively. Three (23.1%) patients with SCAND died of the disease. In contrast, neither metastasis nor mortality was confirmed in the EMPSGC cases. Immunoexpression of the androgen receptor, c-Myb, and MUC2 was limited in SCAND, whereas EMPSGC frequently expressed these immunomarkers. GATA3 P409Afs*99 extension mutations were detected in 7 (53.8%) of the 13 SCAND cases, using Sanger or panel sequencing. All 7 SCAND cases with GATA3 mutations were located in the genital, inguinal, or lower abdominal regions, whereas 5 of the other 6 SCAND cases were located in the anterior upper to mid-trunk. No GATA3 mutations were detected in the EMPSGC cases (0/5, 0%). These clinicopathologic and genetic findings support SCAND as a tumor entity distinguishable from EMPSGC. In addition, the characteristic frameshift extension mutations in GATA3 contribute to the establishment of the tumor-type concept of SCAND.

Primary Mucinous Carcinoma of Skin: A Rare Cutaneous Neoplasm. Clinicopathologic Features, Differential Diagnoses, and Review of Literature

ABSTRACT

Primary mucinous carcinoma of the skin (PMCS) is a rare malignant neoplasm of sweat gland origin, with an incidence of 0.07 per million. Histologically, it may be difficult to differentiate it from metastatic mucinous carcinomas of the skin. A case of PMCS is reported here in a 59-year-old woman who presented with a lesion on the right lower eyelid. Histological examination revealed features of mucinous adenocarcinoma. The main differential diagnosis was metastatic mucinous adenocarcinoma; however, the lack of colorectal and lung markers and the presence of focal in situ components were consistent with the diagnosis of PMCS. PMCS and breast mucinous carcinoma share immunohistochemical markers, such as GCDFP-15 and mammaglobin; however, focal in situ component with the presence of myoepithelial cells in the tumor ruled out metastatic mucinous carcinoma of breast origin. The subsequent mammograms did not reveal any breast lesions. Colonoscopy did not show any evidence of colonic malignancy, and imaging studies (CT scan) did not show any evidence of neoplasm in the body. These findings were in keeping with a diagnosis of PMCS. The present case emphasizes the importance of clinicopathological correlation, histopathology, and immunohistochemistry in the accurate diagnosis of PMCS and summarizes the literature on these rare cutaneous neoplasms.

Primary high-grade neuroendocrine carcinoma with positive steroid hormone receptors arising in the inguinal skin: A case report of An exceedingly rare entity

INTRODUCTION

Neuroendocrine tumors usually arise from the gastrointestinal and pulmonary tracts and rarely from the skin. We report a unique case of high-grade neuroendocrine carcinoma with positive steroid hormone receptors in the primary skin of the groin.

CASE PRESENTATION

A 79-year-old female presented with a lump in her left inguinal region for 15 years that grew gradually. The tumor cells were arranged in sheets, solid nests, and bands within a rich network of thin-walled capillaries. Mucin was abundant in the stroma, and the tumor cells exhibited high-grade lesions, significant necrosis, and frequent mitosis, with small scattered foci of low-grade components. Immunohistochemistry revealed that the tumor cells diffusely and strongly expressed cytokeratin, synaptophysin, chromogranin A, GATA3, CAM5.2, and estrogen and progesterone receptors; partially expressed AR and GCDFP15.

DIAGNOSIS

Based on pathological morphology, and immunohistochemical staining, it was confirmed as Primary high-grade neuroendocrine carcinoma with positive steroid hormone receptors arising in the inguinal skin. The patient underwent resection of the inguinal tumor and left inguinal lymph node dissection.

INTERVENTIONS

The patient has been followed up for 16 months and has not undergone further examinations or received additional treatment. There is no evidence of tumor recurrence at the site of the original surgical resection, and the patient general condition is satisfactory.

CONCLUSIONS

The morphology of this tumor is unique and previously unreported, further expanding the possible pathogenesis and histological morphologies of this tumor type.

Primary Cutaneous Mucinous Carcinoma: A Review of the Literature

BACKGROUND

Primary cutaneous mucinous carcinoma (PCMC) is an exceedingly rare, low-grade tumor that histologically resembles mucinous carcinoma from other primary sites, such as the breast, gastrointestinal tract, and lungs.

OBJECTIVE

The purpose of this article was to review the current literature on PCMC as it relates to epidemiology, clinical presentation, histopathology, immunohistochemistry, treatment, and prognosis.

MATERIALS AND METHODS

An extensive literature review was conducted using PubMed and Ovid MEDLINE to identify articles related to PCMC.

RESULTS

Several hundred cases have been reported in the medical literature, and surgical resection, whenever feasible, is the standard of care.

CONCLUSION

The diagnosis of primary cutaneous mucinous carcinoma is one of exclusion, requiring a metastatic work-up to rule out distant primary. Mohs micrographic surgery is a tissue sparing technique that allows complete margin control of these rare neoplasia.

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.

Metastatic Endocrine Mucin-Producing Sweat Gland Carcinoma to the Lung: A Case Report

Endocrine mucin-producing sweat gland carcinoma (EMPSGC) is a rare, low-grade neuroendocrine neoplasm previously believed to be indolent in nature. There have only previously been six reported cases of metastases and none of thoracic structures. This case shows a metastatic EMPSGC in a 72-year-old male with a complex oncologic history and is the first reported case of metastases to the lung. As increased recognition of this entity continues to grow, it is important to consider it as part of the differential in mucinous and/or neuroendocrine neoplasms for appropriate management. This case adds to the oncologic literature by demonstrating a rare cutaneous neoplasm and emphasizing its metastatic potential.

Cutaneous Neuroendocrine Mucinous Carcinomas Are Low-grade But May Be Associated With Other Cancers

Primary cutaneous mucinous sweat gland carcinoma is said to be prognostically stratifiable by neuroendocrine differentiation, however, this assertion is based on historical data and older staining techniques. We aimed to evaluate the percentage of mucinous and nonmucinous adnexal tumors expressing the newer, more sensitive neuroendocrine marker insulinoma-associated protein 1 (INSM1), and to assess clinicopathologic features in patients cohorted by this phenotype. Of 12 available adnexal/cutaneous adenocarcinomas, 9 were mucinous, 3/9 of which were INSM1-negative, and 2/3 with nodal metastases. Of 3 nonmucinous cases, all were INSM1-negative, 1/3 with nodal metastasis, and 2/3 with lymphovascular invasion. In contrast, of 6 mucinous INSM1-positive cases, no cases had LVI or metastasis, however, 3 patients died during follow-up, 2 from breast or urothelial cancer. A fourth patient developed breast carcinoma. INSM1-positive tumors, from cheek (3), scalp (2), and chin (1) were estrogen receptor and progesterone receptor positive. No cases of apocrine adenoma or hidrocystoma, basal cell, or sebaceous carcinoma labeled with INSM1. While most primary cutaneous mucinous carcinomas are of the neuroendocrine type, our study confirms the presence of occasional non-neuroendocrine mucinous carcinomas. We validate the association of such tumors and nonmucinous non-neuroendocrine adnexal carcinoma with intermediate-grade behavior, including lymph node metastases, but not death. Conversely, neuroendocrine expressing primary cutaneous mucinous carcinoma may represent the well-differentiated neuroendocrine neoplasm/neuroendocrine tumor primary to skin, with low-grade behavior, but attendant risk of germline susceptibility to other aggressive extracutaneous tumors. Routine assessment of cutaneous adnexal carcinoma with INSM1 and longer term follow-up and cancer screening of patients with positive staining is recommended.

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.

Cytological findings in a case of endocrine mucin-producing sweat gland carcinoma with metastasis to salivary glands

Endocrine mucin‐producing sweat gland carcinoma (EMPSGC) was previously considered an indolent skin tumour without metastasis. This report describes a case of metastatic EMPSGC affecting left parotid and submandibular glands, and its features on aspiration cytology.

Challenges in the diagnosis and treatment of the malignant adnexal neoplasms of the head and neck

PURPOSE OF REVIEW

The current review is to present the current knowledge regarding epidemiology, diagnostics, and management of malignant adnexal neoplasms (MANs).

RECENT FINDINGS

Immunotherapy and gene-related therapies are still being developed as the methods of salvage treatment in advanced and disseminated cases: CACNA1S, ATP2A1, RYR1, and MYLK3, as well as p53 or the JAK/STAT pathways, may be therapeutic targets; the efficiency of talimogene laherparepvec and nivolumab is assessed.

SUMMARY

MANs are rare tumors, but due to the aging of population their incidence is increasing. Their clinical presentation is unspecific, which makes the diagnosis challenging. Histopathological assessment is difficult even for experienced pathologists. Mohs micrographic surgery or wide local excision are recommended to treat primary lesions. Adjuvant radiotherapy may be beneficial in case of insufficient or positive surgical margins, in nodal metastases, in selected types of MANs like sebaceous, trichilemmal, and pilomatrix carcinomas, and as the induction treatment in large tumors located in medically fragile or cosmetically important regions. The role of chemotherapy is not well defined; however, it is recommended in distant metastases. Immunotherapy can improve the prognosis in advanced stage of the disease.

Recurrent Neuroendocrine Primary Cutaneous Mucinous Carcinoma of the Scalp After Complete Excision

ABSTRACT

Primary cutaneous mucinous carcinoma is a rare, indolent malignancy with a debated history regarding cell of origin. Recurrence is rare but has been documented in up to a third of cases. Recent literature reviews have recognized 2 possible subtypes-neuroendocrine and nonneuroendocrine- with different possible prognostic implications for patients. We describe a case of recurrent primary cutaneous mucinous carcinoma in a 50-year-old man with subtle neuroendocrine features not initially recognized on routine H&E staining but highlighted by immunohistochemical studies. We underscore the importance of immunohistochemical use in these rare cases and emphasize that awareness of these neuroendocrine and nonneuroendocrine subtypes is essential for a complete diagnosis.

Primary Cutaneous Mucinous Carcinoma Monitoring: A Role for CA15.3 and CEA?

Primary cutaneous mucinous carcinoma (PCMC) is a rare malignant skin adnexal tumor. Recurrences are most often localized, and long-term follow-up after complete surgery consists essentially of self-examination of skin. We report one case of metastatic PCMC with elevated levels of serum CEA and CA15.3. Because of the difficulty to differentiate PCMC and metastasis of mucinous breast cancer, the hypothesis of a metastasized breast cancer was ruled out. These tumor markers contributed to the monitoring of the metastatic disease. Since metastatic disease was diagnosed after several years of seeming complete remission, CEA and CA15.3 would likely have allowed the clinicians to detect the relapse earlier. Although the use of tumor biomarkers in PCMC is not rooted in clinical practice and not mentioned in guidelines, we suggest that CEA and CA15.3 could be of particular interest to monitor and detect early metastatic PCMC.

Sweat Gland Carcinoma With Neuroendocrine Differentiation of the Areola as a Potential Clinicopathologic Mimicker of Male Breast Carcinoma and Syringocystadenocarcinoma Papilliferum

ABSTRACT

Sweat gland carcinoma with neuroendocrine differentiation (SCAND) is a newly proposed tumor entity of primary cutaneous apocrine/eccrine adnexal tumor with neuroendocrine differentiation. The histopathologic variations are not yet well known. In this article, we present a case of SCAND mimicking male breast cancer and syringocystadenocarcinoma papilliferum. A 68-year-old man presented with a reddish 12-mm nodule on his left areola. No lymph node or distant metastases were observed. The patient was disease free 1 year and 9 months after the tumor was surgically resected but died of cerebral hemorrhage. Histopathological examination revealed a predominantly intradermal tumor with marked syringotropism, mimicking a component of mammary ductal carcinoma in situ. In addition, another tissue section displayed a cup-shaped papillated tumor with syringocystadenocarcinoma papilliferum-like features, which were also seen because of marked syringotropism. Diffuse immunoexpression of cytokeratin 7, cytokeratin 19, chromogranin A, synaptophysin, INSM1, estrogen receptor, carcinoembryonic antigen, epithelial membrane antigen, and GATA3 was observed in the tumor, but no BRAF immunoexpression was seen. The present case would help us to understand the histopathological variation and differential diagnosis of SCAND. The histopathological diagnosis of male breast cancer or syringocystadenocarcinoma papilliferum should be made by ruling out SCAND.

Large Cell Neuroendocrine Carcinoma of the Skin/Conjunctiva: A Series of 6 Cases including 1 Combined Case With Squamous Cell Carcinoma

ABSTRACT

This study sought to reveal the clinicopathologic characteristics of large cell neuroendocrine carcinoma (LCNEC) of the skin/conjunctiva. The retrieved patients included 3 men and 3 women with a median age of 85 (63-95) years. All lesions occurred on the face, including the ears, with a median tumor size of 11.5 (7-65) mm. Lymph node metastasis was observed in 5 (83%) of 6 cases, and distant metastasis was noted in 2 (33%). One patient (17%) who had a 13-mm-sized tumor died of the tumor 13 months after excision. All tumors were mainly located in the dermis, and one of them also exhibited intraepithelial spreading. The cytology resembled that of an LCNEC in other organs. No adnexal differentiation was observed. Five cases were of the pure type, but one had a component of squamous cell carcinoma. Immunoreactivities for CAM5.2, CK7, CK19, BerEP4, epithelial membrane antigen, neuron-specific enolase, synaptophysin, c-KIT, GATA3, and bcl-2 were frequently present, but CK20, neurofilament, Merkel cell polyomavirus large T antigen, mammaglobin, estrogen receptor, HER2, and TTF1 were completely negative in all cases. Mutant-pattern immunostaining of p53, PTEN, and Rb was frequently observed. The Ki67 rate exceeded 70% in all cases. LCNEC of the skin/conjunctiva is a morphologically-defined group of primary cutaneous/conjunctival neuroendocrine neoplasm, although it may be heterogeneous similar to other-site LCNEC or Merkel cell carcinoma. This study highlighted the predominant location for the face, high metastatic and lethal potential, possible combination with other tumor components, and frequent mutant-type immunoexpressions of p53, PTEN, and Rb in this tumor group.

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.

Investigation of the RB1-SOX2 axis constitutes a tool for viral status determination and diagnosis in Merkel cell carcinoma

MCC (Merkel cell carcinoma) is an aggressive neuroendocrine cutaneous neoplasm. Integration of the Merkel cell polyomavirus (MCPyV) is observed in about 80% of the cases, while the remaining 20% are related to UV exposure. Both MCPyV-positive and -negative MCCs-albeit by different mechanisms-are associated with RB1 inactivation leading to overexpression of SOX2, a major contributor to MCC biology. Moreover, although controversial, loss of RB1 expression seems to be restricted to MCPyV-negative cases.The aim of the present study was to assess the performances of RB1 loss and SOX2 expression detected by immunohistochemistry to determine MCPyV status and to diagnose MCC, respectively.Overall, 196 MCC tumors, 233 non-neuroendocrine skin neoplasms and 70 extra-cutaneous neuroendocrine carcinomas (NEC) were included. SOX2 and RB1 expressions were assessed by immunohistochemistry in a tissue micro-array. Diagnostic performances were determined using the likelihood ratio (LHR).RB1 expression loss was evidenced in 27% of the MCC cases, 12% of non-neuroendocrine skin tumors and 63% of extra-cutaneous NEC. Importantly, among MCC cases, RB1 loss was detected in all MCPyV(-) MCCs, while MCPyV( +) cases were consistently RB1-positive (p < 0.001). SOX2 diffuse expression was observed in 92% of the MCC cases and almost never observed in non-neuroendocrine skin epithelial neoplasms (2%, p < 0.0001, LHR +  = 59). Furthermore, SOX2 diffuse staining was more frequently observed in MCCs than in extra-cutaneous NECs (30%, p < 0.001, LHR +  = 3.1).These results confirm RB1 as a robust predictor of MCC viral status and further suggest SOX2 to be a relevant diagnostic marker of MCC.

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.

Molecular pathology of skin adnexal tumours

AIMS

Tumours of the cutaneous adnexa arise from, or differentiate towards, structures in normal skin such as hair follicles, sweat ducts/glands, sebaceous glands or a combination of these elements. This class of neoplasms includes benign tumours and highly aggressive carcinomas. Adnexal tumours often present as solitary sporadic lesions, but can herald the presence of an inherited tumour syndrome such as Muir-Torre syndrome, Cowden syndrome or CYLD cutaneous syndrome. In contrast to squamous cell carcinoma and basal cell carcinoma, molecular changes in adnexal neoplasia have been poorly characterised and there are few published reviews on the current state of knowledge.

METHODS AND RESULTS

We reviewed findings in peer-reviewed literature on molecular investigations of cutaneous adnexal tumours published to June 2021.

CONCLUSIONS

Recent discoveries have revealed diverse oncogenic drivers and tumour suppressor alterations in this class of tumours, implicating pathways including Ras/MAPK, PI3K, YAP/TAZ, beta-catenin and nuclear factor kappa B (NF-κB). These observations have identified novel markers, such as NUT for poroma and porocarcinoma and PLAG1 for mixed tumours. Here, we provide a comprehensive overview and update of the molecular findings associated with adnexal tumours of the skin.

Sweat-gland carcinoma with neuroendocrine differentiation (SCAND): a clinicopathologic study of 13 cases with genetic analysis

Low-grade neuroendocrine carcinoma of the skin (LGNECS) was proposed in 2017 as a new primary cutaneous neoplasm with neuroendocrine differentiation; however, it is not yet well known due to its rarity. Herein, we perform a detailed clinicopathologic analysis of 13 cases as well as panel DNA sequencing in three cases. The study included 12 males and 1 female with a median age of 71 (43-85) years. All lesions occurred on the ventral trunk. The mean tumor size was 2.2 (0.8-11.0) cm. The histopathology resembled that of well-differentiated neuroendocrine tumors (NETs) in other organs, but intraepidermal pagetoid spreading was seen in 8 (61.5%) cases and stromal mucin deposits in 4 (30.8%). Immunoreactivity for CK7, CK19, EMA, BerEP4, CEA, chromogranin A, synaptophysin, INSM1, GCDFP15, GATA3, ER, and bcl-2 were present in varying degrees in all tested cases. PTEN c.165-1G>A splice site mutation was detected by panel sequencing in one case, and GATA3 P409fs*99 and SETD2 R1708fs*4 in another case. Lymph node metastasis was seen significantly in cases with tumor size >2.0 cm [8/8 (100%) vs. 1/5 (20%)]. All three cases with size >3.0 cm were in unresectable advanced-stage [3/3 (100%) vs. 1/10 (10%)], and two of the three patients succumbed to the disease. The two cases of death revealed mild nuclear atypia (mitosis: 1/10 HPFs) and moderate nuclear atypia (2/10 HPFs). Thus, tumor size would be a better prognostic factor than nuclear atypia, mitotic count, and Ki67 index, unlike in NETs. These clinicopathologic and immunohistochemical features would represent the characteristics as skin adnexal tumors with apocrine/eccrine differentiation rather than NETs; therefore, we rename it as sweat-gland carcinoma with neuroendocrine differentiation (SCAND).

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.

Endocrine Mucin Producing Sweat Gland Carcinoma with Metastasis to Parotid Gland: Not as Indolent as Perceived?

Endocrine mucin-producing sweat gland carcinoma (EMPSCG) is a rare, low-grade cutaneous adnexal neoplasm with evidence of neuroendocrine differentiation, predominantly involving the eyelids of elderly. It has a striking resemblance to solid papillary carcinoma of breast which similarly displays neuroendocrine features. EMPSGC is considered a precursor of cutaneous mucinous carcinoma, and the term "mucinous carcinoma" is also recommended for hybrid lesions which reveal an invasive mucinous component associated with EMPSGC. While local recurrences are well- documented in EMPSGC, metastases had not been encountered until very recently; two reports in the past year have described metastases from eyelid EMPSGC to the parotid gland after a prolonged interval from the primary presentation. We report the case of a 78-year-old male with eyelid EMPSGC metastatic to the parotid gland nine years after excision of the primary tumor, which had initially been diagnosed as a poorly differentiated carcinoma. Development of metastasis after a prolonged interval is similar to both the previously described cases, and emphasizes the need to reevaluate the stated indolent nature of this neoplasm. It also aims to draw attention of pathologists to this uncommon tumor of the eyelid which is often misdiagnosed on primary presentation.

Utility of Insulinoma-Associated Protein 1 (INSM1) and Mucin 2 (MUC2) Immunohistochemistry in the Distinction of Endocrine Mucin-Producing Sweat Gland Carcinoma From Morphologic Mimics

ABSTRACT

Endocrine mucin-producing sweat gland carcinoma (EMPSGC) is a rare low-grade adnexal malignancy with a predilection for the eyelids of elderly White women, which is associated with invasive mucinous carcinoma with endocrine features in one-third of cases. EMPSGC is characterized by the presence of neuroendocrine differentiation and mucin production. However, EMPSGC displays a variety of architectural patterns including solid, cribriform, papillary, and cystic growth. In addition, EMPSGC may also display nonendocrine cytologic features, such as apocrine change. Because of their variable appearance, EMPSGC can show significant morphologic overlap with certain histologic mimics, namely basal cell carcinoma, hidrocystoma, apocrine hidradenoma, and tubular adenoma. In addition, the often limited sampling of this anatomically delicate area can make the diagnosis of EMPSGC challenging. EMPSGC expresses neuroendocrine markers, including synaptophysin and chromogranin, often in a focal distribution. However, insulinoma-associated protein 1 (INSM1) has been found to be a more sensitive marker for EMPSGC. Recent studies have also demonstrated the expression of the gel-forming mucin 2 (MUC2) in EMPSGC, possibly signifying a lacrimal or conjunctival origin of these neoplasms. In this article, we discuss EMPSGC in the context of its histologic mimics (BCC, hidrocystoma, apocrine hidradenoma, and tubular adenoma) and we investigate the utility of the immunohistochemical expression of INSM1 and MUC2 in the distinction of EMPSGC from them. We demonstrate that INSM1 and MUC2 can reliably distinguish EMPSGC from these histologic mimics.

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.

A case of endocrine mucin-producing sweat gland carcinoma with distant metastasis

Endocrine mucin-producing sweat gland carcinoma (EMPSGC) is a rare cutaneous adnexal neoplasm typically arising on the face of older individuals, most commonly around the eyelids. Histopathologic features include a circumscribed proliferation of low-grade epithelioid cells with areas of cystic and cribriform growth, foci of intracytoplasmic and extracellular mucin, and coexpression of endocrine, neuroendocrine, and cytokeratin markers by immunohistochemistry. Given histopathologic and immunohistochemical similarities, EMPSGC is often likened to solid papillary carcinoma of the breast and endocrine ductal carcinoma in situ, and is thought by many to represent a forme fruste of mucinous carcinoma of the skin. To date, the vast majority of reported cases of EMPSGC have been described as having indolent behavior, with no cases of distant metastasis yet reported. Here we report a unique case of EMPSGC that recurred over several years following standard surgical excision and Mohs micrographic surgery, with subsequent metastasis to the parotid gland and axial skeleton.

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.

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.