Sebaceous Neoplasms

Histopathological and Immunohistochemical Characterization of Sebaceous Adenoma and Epithelioma in Dogs

Sebaceous gland tumors are neoplasms originating from the sebaceous gland and are the third most common type of skin tumor, accounting for 21-35% of all cutaneous neoplasms in dogs. According to their histopathological characteristics, sebaceous gland tumors can be classified into adenoma as a benign tumor and epithelioma as a malignant tumor. Sebaceous epithelioma is distinguished from sebaceous adenoma by containing 90% or more reserve cells. However, this simple numerical criterion is insufficient to histologically distinguish between epitheliomas and adenomas. In addition, sebaceoma in humans, a similar tumor to sebaceous epithelioma, is a term used for tumors with more than 50% of reserve cells, unlike epithelioma. Therefore, we aimed to compare and characterize the histological and immunohistochemical profiles of comprehensive sebaceous adenoma, epithelioma, and borderline tumors that have more than 50% but less than 90% of reserve cells. A total of 14 canine sebaceous tumors were diagnosed as seven adenomas, four borderline tumors, and three epitheliomas. Histologically, the sebaceous adenomas showed nodules consisting of mature sebocytes surrounded by monolayer basaloid cells. In contrast, the portion of the reserve cells was increased, the portion of lipidized cells was decreased, and the majority of lipidized cells were found to be immature in sebaceous epithelioma. In the sebaceous adenomas, necrosis was not observed and mitotic figures were rarely seen. However, necrosis and mitotic figures were highly frequent in both borderline tumor and sebaceous epithelioma. Immunohistochemistry revealed that borderline tumor and sebaceous epithelioma showed significantly higher expression against Ki-67 than sebaceous adenoma. We conclude that it is more accurate to employ the cut-off value of 50% reserve cells in humans rather than the current 90% reserve cells for classifying sebaceous gland tumors in dogs, thereby providing new insight into the characterization of the sebaceous gland tumors.

Sebaceous hyperplasia of the eyelid: A comprehensive case report and literature review

Introduction

Sebaceous gland hyperplasia of the eyelids, known as adenomatoid or pseudoadenomatous hyperplasia, is a rare benign condition. Optimal management strategies for this specific type of eyelid tumor require further investigation.

Case presentation

The patient presented with a 21-year history of a progressively enlarged mass in the right lower eyelid. Previous treatments, including laser photocoagulation and surgical excision, have failed to prevent recurrence. The mass, characterized by a firm texture and low mobility, has raised concerns regarding malignancy. However, histopathological examination following surgical excision identified the mass as sebaceous gland hyperplasia. The patient's medical history was notable for benign gastrointestinal and intestinal polyps with no evidence of malignancy.

Conclusions

A final diagnosis of eyelid sebaceous gland hyperplasia was established after surgical excision and comprehensive histopathological analyses. The patient's successful recovery without recurrence over a three-month follow-up period post-surgery highlights the efficacy of the surgical approach and the use of intraoperative frozen section pathological examination.

Androgen Receptor Immunohistochemistry is Superior to PRAME for the Differentiation of Sebaceous Carcinoma From Primary Cutaneous Basaloid Mimics

ABSTRACT

Cutaneous sebaceous neoplasia comprises a spectrum of disease ranging from benign adenomas to malignant carcinomas. The hallmark of these lesions is sebaceous differentiation. However, poorly-differentiated sebaceous carcinoma (SC), which lacks significant overt sebaceous differentiation, can show morphologic overlap with a variety of other basaloid cutaneous neoplasms. The accurate classification of SC is essential not only for diagnosis, but also because of the potential association with Muir-Torre syndrome. Androgen receptor (AR) is a sensitive, but not entirely specific immunohistochemical marker that has been used for the diagnosis of SC. PReferentially expressed Antigen in MElanoma (PRAME) demonstrates strong cytoplasmic labeling of mature sebocytes and has been reported to be expressed in a variety of sebaceous neoplasms, including in the basaloid cell component. Therefore, we sought to compare the diagnostic use of cytoplasmic PRAME expression with that of AR for the distinction of SC from a cohort of basaloid cutaneous mimics; namely basal cell carcinoma, basaloid squamous cell carcinoma, pilomatricoma, cutaneous lymphadenoma, and extra-mammary Paget disease. We report that cytoplasmic PRAME expression is uncommon in poorly differentiated SC, and although specific, it shows very low sensitivity (22%). In contrast, AR was moderately sensitive (66%) and highly specific (92%) for the distinction of SC from basaloid mimics. These attributes, in addition to the nuclear expression of AR in the sebocytic and basaloid components of SC, suggest that AR is superior to PRAME for the diagnosis of SC.

Sebaceous Adenoma: A Dermoscopic Case Perspective

This report focuses on sebaceous skin tumors, specifically sebaceous adenoma, sebaceoma, and sebaceous carcinoma, along with their association with Muir-Torre syndrome (MTS). A clinical case of a 25-year-old male with a suspected sebaceous neoplasm based on dermoscopy appearance is presented. The histopathological examination confirmed the diagnosis and surgical management resulted in successful treatment. The report highlights the importance of considering differential diagnoses and utilizing dermoscopy for accurate evaluation of these rare skin tumors.

Borderline Malignant Sebaceoma of the Auricle: A Case Report

Sebaceoma is a rare benign tumor arising from the sebaceous gland of the skin. Sebaceoma often occurs on the head and neck but rarely on the ears. We present the case of a 78-year-old female patient with a two-year history of a protruding mass in her left ear. Physical examination revealed a well-circumscribed plaque in the crus of the helix of the left ear. A wide local excisional biopsy was taken, and the mass was subjected to histopathologic assessment. While the mass showed cytological findings indicating sebaceoma, it also presented malignant features architecturally and immunohistochemically. Based on these findings, the tumor was regarded as a sebaceoma of borderline malignancy.

Supplementary Information

The online version contains supplementary material available at 10.1007/s12070-023-03552-4.

Machine learning for classification of cutaneous sebaceous neoplasms: implementing decision tree model using cytological and architectural features

BACKGROUND

This observational study aims to describe and compare histopathological, architectural, and nuclear characteristics of sebaceous lesions and utilized these characteristics to develop a predictive classification approach using machine learning algorithms.

METHODS

This cross-sectional study was conducted on Iranian patients with sebaceous tumors from two hospitals between March 2015 and March 2019. Pathology slides were reviewed by two pathologists and the architectural and cytological attributes were recorded. Multiple decision tree models were trained using 5-fold cross validation to determine the most important predictor variables and to develop a simple prediction model.

RESULTS

This study assessed the characteristics of 123 sebaceous tumors. Histopathological findings, including pagetoid appearance, neurovascular invasion, atypical mitosis, extensive necrotic area, poor cell differentiation, and non-lobular tumor growth pattern, as well as nuclear features, including highly irregular nuclear contour, and large nuclear size were exclusively observed in carcinomatous tumors. Among non-carcinomatous lesions, some sebaceoma and sebaceous adenoma cases had features like high mitotic activity, which can be misleading and complicate diagnosis. Based on multiple decision tree models, the five most critical variables for lesion categorization were identified as: basaloid cell count, peripheral basaloid cell layers, tumor margin, nuclear size, and chromatin.

CONCLUSIONS

This study implemented a machine learning modeling approach to help optimally categorize sebaceous lesions based on architectural and nuclear features. However, studies of larger sample sizes are needed to ensure the accuracy of our suggested predictive model.

Detection of sebaceous gland hyperplasia with dermoscopy and reflectance confocal microscopy

Background

Sebaceous gland hyperplasia (SGH) is a benign cutaneous proliferation of the sebaceous glands that are mostly present on the face or the neck of older adults. They typically appear as single or multiple soft umbilicated papules; however, in challenging cases, it can be difficult to distinguish them from trichoepitheliomas, base cell carcinomas, or other tumors. Although pathological results have diagnostic value, the significance of non-invasive examinations in diagnosis and differential diagnosis is also worth exploring.

Objectives

This study aimed to describe the dermoscopic and reflectance confocal microscopy (RCM) features of SGH.

Methods

A total of 31 patients diagnosed with SGH, according to clinical and histopathological standards, were examined using dermoscopy and RCM between March 2018 and January 2022.

Results

Dermoscopically, lesions revealed a yellowish-red background and a faint-yellow background in 25 (80.65%) and six cases (19.35%), respectively. White-yellowish lobulated structures in the center of the lesion were present in 31 patients (100%) and umbilications in 19 patients (61.29%). Crown vessels at the periphery of the lesions were observed in 11 patients (35.48%), whereas irregular linear vessels were observed on the surface of the lesions in 18 patients (58.06%). Under RCM, all lesions presented a honeycomb pattern in the epidermis and the typical morulae-shaped sebaceous lobules in the dermis. A dilated follicular infundibulum was observed in 15 patients (48.39%) and dilated vessels in 26 patients (83.87%).

Conclusion

Dermoscopy and RCM enabled us to describe the imaging features of SGH. Combining these two useful tools provides a non-invasive basis for accurate clinical diagnosis.

Sebaceous Neoplasms

Sebaceous neoplasms describe a group of tumors with sebaceous differentiation commonly seen in lesions located primarily in the face and neck. The majority of these lesions are benign, while malignant neoplasms with sebaceous differentiation are uncommon. Sebaceous tumors present a strong association with the Muir-Torre Syndrome. Patients suspected with this syndrome should undergo neoplasm excision, followed by histopathologic and additional immunohistochemistry and genetics examinations. Clinical and dermoscopic features of the sebaceous neoplasms, as well as management procedures collected from the literature analysis regarding sebaceous carcinoma, sebaceoma/sebaceous adenoma, and sebaceous hyperplasia are described in the current review. A special note is made for describing the Muir-Torre Syndrome in patients presenting multiple sebaceous tumors.

Microsatellite Instability in Near East Sebaceous Neoplasms: Toward Improved Prediction

Sebaceous neoplasms (SN) comprise a heterogeneous spectrum of tumors with different biological behaviors. In the Near-East Region (NER), microsatellite instability (MSI) in SN's development, and its correlation with the clinicopathologic features of tumors is not well elucidated. A cohort of 225 SN patients (40 benign SNs and 185 sebaceous carcinomas) from the NER was retrospectively reviewed. Clinical variables and available follow-up information were recorded. MSI proteins (MLH1, MSH2, MSH6, and PMS2) as well as P53, P16, EMA, CD8, and PDL-1 expressions were examined by immunohistochemistry. Detection of human papilloma virus was determined by polymerase chain reaction. Microscopic features such as mitotic count and tumor-infiltrating lymphocytes were documented. A minority of SNs from benign (n=2) or malignant (n=3) tumors in the NER exhibit MSI (2.2%). MSI is exclusively found in patients with extraocular lesions (back, n=5) and presented a poor outcome. Among these, PMS2 protein was mostly lost (average=80%, n=4). SN with MSI exhibited a significant increase in p53 expression, (average=62.10%, P=0.002). There was no significant correlation between MSI status and any of the following: PD-L1, CD8, p16, and human papilloma virus infection. Microscopically, SN with MSI show significantly higher mitotic count, cystic changes and increased tumor-infiltrating lymphocytes. MSI is rarely found in NER's SN. When detected, it is exclusively in extraocular SNs with minimal predicative microscopic features and worse outcome.

Comparison of adipophilin and recently introduced PReferentially expressed Antigen in MElanoma immunohistochemistry in the assessment of sebaceous neoplasms: A pilot study

BACKGROUND

We and others have noticed consistent staining of sebaceous glands with PReferentially expressed Antigen in MElanoma (PRAME). We aimed to determine whether PRAME was as sensitive, specific, and interpretable as adipophilin for distinguishing sebaceous neoplasms (SNs) from other neoplasms.

METHODS

Twenty SNs and 32 control cases were stained for PRAME and adipophilin. Extent of staining was scored as follows: 0, no staining; 1, <5% positivity; 2, 5% to 50% positivity; and 3, >50% positivity. Intensity was scored as negative, weak, moderate, or strong. A composite score was determined by adding the scores for extent and intensity.

RESULTS

PRAME had positive composite scores in all 20 SNs in the more differentiated areas, whereas adipophilin had positive composite scores in 19/20 cases. PRAME showed positivity in the basaloid cells in 15/16 cases, whereas adipophilin was positive in 14. Among controls, PRAME and adipophilin had positive composite scores in 3/32 cases and 6/32 cases, respectively.

CONCLUSIONS

PRAME and adipophilin are comparable in terms of distribution and intensity for staining sebocytes. In the basaloid cells, PRAME expression is often more diffuse and easier to detect than adipophilin. In comparing the SNs to the controls, PRAME was more sensitive and more specific than adipophilin. PRAME could be used as an additional marker of sebaceous differentiation in everyday practice.

Diagnosis and analysis of a sebaceous gland tumour of the external acoustic meatus in a Cocker Spaniel dog

Sebaceous gland tumour (SGT) is a rare tumour with a low incidence rate, which mainly occurs in the eyelid and periocular sebaceous gland. In 2019, our laboratory received a case involving a sebaceous gland tumour of the external auditory meatus for pathological diagnosis. It is a rare malignant tumour in the whole body. Data regarding a sebaceous gland tumour in the dogís external auditory meatus are few. This case is instructive for veterinary diagnosis and treatment. The dog recovered well after surgery at the outpatient department, and no recurrence was observed in the follow-up visit one year later. This study will help the identification of SGT in Spaniel dogs.

TERT promoter mutation in sebaceous neoplasms

TERT promoter (TERTp) mutations widely occur in multiple human neoplasms, and they have been related to different clinicopathological features. To date, this mutation has not been identified in sebaceous tumors. Here, we analyzed TERTp mutations in 91 sebaceous neoplasms (17 adenomas, 45 sebaceomas, and 29 carcinomas). We detected mutations in 26.7% (8 of 29) of sebaceous carcinomas by pyrosequencing and Sanger sequencing. No mutation was detected in adenomas or sebaceomas. The difference was significant between sebaceoma and carcinoma. The most frequent TERTp mutations were C228T and C250T in 37.5% (3 of 8) of mutated cases each one. The mutation was not associated with poor clinical evolution. Using NGS, 20 of 29 (68.5%) sebaceous carcinomas harbored mutations in 8 of the 30 genes analyzed (TP53, TERTp, EGFR, ATRX, PDGFRA, CDKN2A, PTEN, and ACVR1). With immunohistochemistry, only 1 of 8 (12.5%) TERTp-mutated carcinomas lacked mismatch repair (MMR) protein expression compared to 6 of 21 (31.6%) of non-mutated ones. Sebaceous carcinomas with MMR protein expression had significantly higher frequency of total mutations and TP53 and TERTp mutations than MMR protein-deficient carcinomas. In conclusion, TERTp mutation has been detected in sebaceous carcinomas, and its presence could be useful to differentiate sebaceous carcinoma from sebaceoma, a difficult histopathological challenge.

Ocular Adnexal Adenomatoid Sebaceous Gland Hyperplasia: A Clinical and Immunopathologic Analysis in Relation to the Muir-Torre Syndrome

The purpose of this study is to codify the microscopic diagnostic criteria for ocular adnexal brow and caruncular sebaceous gland hyperplasias (pseudoadenomatoid) that distinguish it from an adenoma. Clinical records and photographs were critically reviewed and microscopic slides were stained with hematoxylin and eosin and immunochemically stained for adipophilin, androgen receptor, p16, p53, a spectrum of cytokeratins, Ki-67 and mismatch repair nuclear protein expression for MLH1, MSH2, PMS2, and MSH6. The patients and their close relatives had no history of cancer. Cytokeratin 7 and especially cytokeratin 17 highlighted the presence of ducts in the hyperplastic lesion, which are not present in adenomas. p16 and p53 were negative and Ki-67 immunostaining demonstrated similar low proliferation indices for normal and hyperplastic glands. The mismatch repair nuclear protein expressions were preserved in both lesions. Histopathologic misdiagnosis of adenomatoid sebaceous gland hyperplasia as an adenoma can lead to the impression of an association with the Muir-Torre syndrome. Cytokeratins 7 and 17 immunostaining can be helpful in highlighting compressed ducts that in exuberant sebaceous gland hyperplasias may lead to a diagnosis of an adenoma (in which ducts are absent). Negative immunostaining for p16 rules out a possible etiologic role of human papillomavirus in hyperplasias and the negative p53 staining indicates the lesions are not truly neoplastic. The preservation of mismatch repair nuclear protein expression rules out the likelihood of the Muir-Torre syndrome. The current cases convincingly establish that sebaceous hyperplasia is not associated with the Muir-Torre syndrome by both clinical findings and immunohistochemical testing.Two yellow lesions, from the brow and caruncle, were examined microscopically and immunohistochemically to establish the diagnosis of sebaceous gland hyperplasia and to rule out the Muir-Torre syndrome.

An updated review of the sebaceous gland and its role in health and diseases Part 2: Pathophysiological clinical disorders of sebaceous glands

Sebaceous glands are sebum-secreting components of pilosebaceous units. In the second of this two-part series, we review the pathologies in which sebaceous glands are primarily and secondarily implicated. They are primarily involved in steatocystoma simplex and multiplex, sebaceous gland hyperplasia, sebaceoma, sebaceous adenoma, sebaceous carcinoma, nevus sebaceus, and folliculosebaceous cystic hamartoma. Sebaceous glands are secondarily involved in acne vulgaris, seborrheic dermatitis, and androgenic alopecia. Steatocystoma multiplex is a benign congenital anomaly presenting as yellow cysts primarily on the upper body. Sebaceous gland hyperplasia is characterized by yellow, telangiectatic papules with a central dell, and it can be treated with topical retinoids or surgical excision. Sebaceoma clinically presents on the head and neck region as a skin-colored nodule and can be distinguished by immunohistochemistry. Stains used in the diagnosis of sebaceous adenoma and carcinoma include epithelial membrane antigen and adipophilin immunoperoxidase. Surgical excision is the preferred treatment for sebaceoma, sebaceous adenoma, and sebaceous carcinoma. Excision is not always indicated for nevus sebaceus. Folliculosebaceous cystic hamartoma is a relatively rare condition exhibiting both epithelial and mesenchymal components. Patients with acne vulgaris commonly present with papules of closed and open comedones displaying hypercornification. Seborrheic dermatitis presents as sharply demarcated yellow or red patches or plaques; antifungal agents, corticosteroids, and combination antifungal/anti-inflammatory therapies are common treatment modalities. As a result of hair follicle miniaturization, females with androgenic alopecia present with diffuse hair thinning, while men tend to present with balding and hairline recession.

Are clinicians successful in diagnosing cutaneous adnexal tumors? a retrospective, clinicopathological study

Background/aim

Cutaneous adnexal tumors (CAT) are rare tumors originating from the adnexal epithelial parts of the skin. Due to its clinical and histopathological characteristics comparable with other diseases, clinicians and pathologists experience difficulties in its diagnosis.We aimed to reveal the clinical and histopathological characteristics of the retrospectively screened cases and to compare the prediagnoses and histopathological diagnoses of clinicians.

Materials and methods

The data of the last 5 years were scanned and patients with histopathological diagnosis of CAT were included in the study.

Results

A total of 65 patients, including 39 female and 26 male patients aged between 8 and 88, were included in the study. The female to male ratio was 1.5, and the mean age of the patients was 46.15 ± 21.8 years. The benign tumor rate was 95.4%, whereas the malignant tumor rate was 4.6%. 38.5% of the tumors were presenting sebaceous, 35.4% of them were presenting follicular, and 18.5% of them were presenting eccrine differentiation. It was most commonly seen in the head-neck region with a rate of 66.1%. When clinical and histopathological prediagnoses were compared, prediagnoses and histopathological diagnoses were compatible in 45% of the cases. Most frequently, it was the basal cell carcinoma, epidermal cyst, and sebaceous hyperplasia identified in preliminary diagnoses.

Conclusion

Cutaneous adnexal tumors are very important, as they can accompany different syndromes and may be malignant. Due to difficulties in its clinical diagnosis, histopathological examination must be performed from suspicious lesions for definitive diagnosis.

Update on the pathology, genetics and somatic landscape of sebaceous tumours

Cutaneous sebaceous neoplasms show a predilection for the head and neck area of adults and include tumours with benign behaviour, sebaceous adenoma and sebaceoma, and sebaceous carcinoma with potential for an aggressive disease course at the malignant end of the spectrum. The majority of tumours are solitary and sporadic, but a subset of tumours may be associated with Lynch syndrome, also known as hereditary non-polyposis colon cancer (HNPCC) and previously referred to as Muir-Torre syndrome (now known to be part of Lynch syndrome). This review provides an overview of the clinical and histological features of cutaneous sebaceous neoplasia with an emphasis on differentiating features and differential diagnosis. It also offers insights into the recently described molecular pathways involved in the development of sebaceous tumours and their association with Lynch syndrome.

Sebaceoma of a Meibomian Gland of the Upper Eyelid

Over a period of 1 year, a 74-year-old man slowly developed a painless left upper eyelid intratarsal mass. The skin was movable over the lesion. At surgery, a well-circumscribed, yellow-white, partially cystic tumor was encountered. Histopathologically it was composed of a random mixture of basaloid and sebaceous cells arranged in interconnecting cords. Immunohistochemical evaluation disclosed epithelial membrane antigen, adipophilin, and cytokeratin 14 positivity. These findings led to the diagnosis of a sebaceoma. The tumor cells abnormally failed to express mismatch repair proteins for MLH1 and PMS2. The patient did not have a personal history of any visceral malignancy, but his father had died at the age of 46 years and a daughter at the age of 33 years from colonic carcinomas. The implications of this periocular sebaceoma for the Muir-Torre syndrome are explored.

Sebaceoma on the scalp simulating a malignant pigmented neoplasia

The correct identification of pigmented nodular lesions of the scalp is often challenging. Despite the importance of clinical patterns and dermoscopy, important adjuvant tools that are usually helpful, their interpretation sometimes is not clear-cut. Here, the authors discuss a case of sebaceoma mimicking a malignant pigmented neoplasia, with conclusive histopathology.

Tumor mutational signatures in sebaceous skin lesions from individuals with Lynch syndrome

BACKGROUND

Muir-Torre syndrome is defined by the development of sebaceous skin lesions in individuals who carry a germline mismatch repair (MMR) gene mutation. Loss of expression of MMR proteins is frequently observed in sebaceous skin lesions, but MMR-deficiency alone is not diagnostic for carrying a germline MMR gene mutation.

METHODS

Whole exome sequencing was performed on three MMR-deficient sebaceous lesions from individuals with MSH2 gene mutations (Lynch syndrome) and three MMR-proficient sebaceous lesions from individuals without Lynch syndrome with the aim of characterizing the tumor mutational signatures, somatic mutation burden, and microsatellite instability status. Thirty predefined somatic mutational signatures were calculated for each lesion.

RESULTS

Signature 1 was ubiquitous across the six lesions tested. Signatures 6 and 15, associated with defective DNA MMR, were significantly more prevalent in the MMR-deficient lesions from the MSH2 carriers compared with the MMR-proficient non-Lynch sebaceous lesions (mean ± SD=41.0 ± 8.2% vs. 2.3 ± 4.0%, p = 0.0018). Tumor mutation burden was, on average, significantly higher in the MMR-deficient lesions compared with the MMR-proficient lesions (23.3 ± 11.4 vs. 1.8 ± 0.8 mutations/Mb, p = 0.03). All four sebaceous lesions observed in sun exposed areas of the body demonstrated signature 7 related to ultraviolet light exposure.

CONCLUSION

Tumor mutational signatures 6 and 15 and somatic mutation burden were effective in differentiating Lynch-related from non-Lynch sebaceous lesions.

Clinico‐pathological predictors of mismatch repair deficiency in sebaceous neoplasia: A large case series from a single Australian private pathology service

Background/Objectives

Loss of expression of mismatch repair (MMR) proteins is frequently observed in sebaceous skin lesions and can be a herald for Lynch syndrome. The aim of this study was to identify clinico‐pathological predictors of MMR deficiency in sebaceous neoplasia that could aid dermatologists and pathologists in determining which sebaceous lesions should undergo MMR immunohistochemistry (IHC).

Methods

An audit of sebaceous skin lesions (excluding hyperplasia) where pathologist‐initiated MMR IHC was performed between January 2009 to December 2016 was undertaken from a single pathology practice identifying 928 lesions from 882 individuals. Lesions were further analysed for differences in gender, age at diagnosis, lesion type and anatomic location, stratified by MMR status.

Results

The 882 individuals (67.7% male) had a mean (SD) age of diagnosis of 68.4 ± 13.3 years. Nearly two‐thirds of the lesions were sebaceous adenomas, with 82.6% of all lesions occurring on the head and neck. MMR deficiency, observed in 282 of the 919 lesions (30.7%), was most common in sebaceous adenomas (210/282; 74.5%). MMR‐deficient lesions occurred predominantly on the trunk or limbs (64.7%), compared with 23.2% in head or neck (P < 0.001). Loss of MSH2 and MSH6 protein expression was most frequent pattern of loss (187/281; 66.5%). The highest AUC for discriminating MMR‐deficient sebaceous lesions from MMR‐proficient lesions was observed for the ROC curve based on subgroups defined by type and anatomic location of the sebaceous lesion (AUC = 0.68).

Conclusion

The best combination of measured clinico‐pathological features achieved only modest positive predictive values, sensitivity and specificity for identifying MMR‐deficient sebaceous skin lesions.

Clinical Features and Association with Visceral Malignancy in 80 Patients with Sebaceous Neoplasms

Background

Sebaceous neoplasm is a rare subgroup of appendageal tumors that differentiate towards sebaceous adnexal structures of the skin and are known to be associated with visceral malignancy.

Objective

We aimed to analyze and compare the clinical data including the past history of associated visceral malignancy in patients with sebaceous carcinoma (SC) and benign sebaceous neoplasms (BSN), such as sebaceous adenomas and sebaceomas.

Methods

We retrospectively reviewed the cases of consecutive patients diagnosed with sebaceous neoplasms. Basic demographic data, past medical history, and clinical data regarding the size, location, and presence of associated visceral malignancies were evaluated.

Results

A total of 80 patients of sebaceous neoplasms (51 SC, 29 BSN) were included. A total of 18 associated visceral malignancies were found in 14 patients (8 SC, 6 BSN). Two patients were diagnosed with subsequent visceral malignancies during the primary work-up process for sebaceous neoplasms. The mean age at diagnosis of the visceral malignancies was 63.9 and 47.5 years for patients with SC and BSN, respectively. The most common site of visceral malignancies was the gastrointestinal (GI) tract. Adenocarcinoma was the most common histologic type of the visceral malignancy noted.

Conclusion

We observed associated visceral malignancies in 15.7% of patients with SC and 20.7% with BSN. Our results suggest a need for screening of visceral malignancies, especially of the GI tract, in patients with sebaceous neoplasms.