Sebomatricoma: a unifying term that encompasses all benign neoplasms with sebaceous differentiation

Seborrheic Keratosis With Sebaceous Differentiation, a Series of 8 Cases and Critical Review of the Literature

ABSTRACT

Seborrheic keratosis with sebaceous differentiation (SKSD) can sometimes raise uncertainty, confuse with other even malignant entities, and lead to overestimation of this harmless variant. Retrospective analysis of the cases diagnosed as SKSD and a search of the pertaining literature were conducted. Eight cases of SKSD were found. Histologically, these lesions show a flat to plate-like outgrowth of basaloid cells with solitary or clustered sebocytes at the bottom of the rete ridges and variable sebaceous ducts with luminal cuticula. The lesions differed in the outgrowth subpattern: flat/macular, acanthotic, or reticulated. No association was found with Muir-Torre syndrome, and no malignant transformation was seen in these lesions. Literature search revealed confusingly designated lesions that simply represented SKSD. SKSD can show several growth patterns as classic SK. This entity is either underreported or even underrecognized. This entity is benign; however, according to the literature, exclusion of an associating Muir-Torre syndrome should be warranted. The published literature about this lesion is confusing and inconsistent. We suggest the avoidance of confusing terminology and particularly the terminus epithelioma for such lesions.

Topics in histopathology of sweat gland and sebaceous neoplasms

This article reviews several topics regarding sweat gland and sebaceous neoplasms. First, the clinicopathological characteristics of poroid neoplasms are summarized. It was recently reported that one-fourth of poroid neoplasms are composite tumors and one-fourth are apocrine type lesions. Recent progress in the immunohistochemical diagnosis of sweat gland neoplasms is also reviewed. CD117 can help to distinguish sweat gland or sebaceous tumors from other non-Merkel cell epithelial tumors of the skin. For immunohistochemical differential diagnosis between sweat gland carcinoma (SGC) other than primary cutanesous apocrine carcinoma and skin metastasis of breast carcinoma (SMBC), a panel of antibodies may be useful, including p63 (SGC⁺ , SMBC^- ), CK5/6 (SGC⁺ , SMBC^- ), podoplanin (SGC⁺ , SMBC^- ) and mammaglobin (SGC^- , SMBC⁺ ). Comparison of antibodies used for immunohistochemical diagnosis of sebaceous carcinoma (SC) suggests that adipophilin has the highest sensitivity and specificity. Some authors have found that immunostaining for survivin, androgen receptor and ZEB2/SIP1 has prognostic value for ocular SC, but not extraocular SC. In situ SC is rare, especially extraocular SC, but there have been several recent reports that actinic keratosis and Bowen's disease are the source of invasive SC. Finally, based on recent reports, classification of sebaceous neoplasms into three categories is proposed, which are sebaceoma (a benign neoplasm with well-defined architecture and no atypia), borderline sebaceous neoplasm (low-grade SC; an intermediate tumor with well-defined architecture and nuclear atypia) and SC (a malignant tumor with invasive growth and evident nuclear atypia).

Circumscribed sebaceous neoplasms: a morphological, immunohistochemical and molecular analysis

Sebaceous neoplasms encompass a range of lesions, including benign entities such as sebaceous adenoma and sebaceoma, as well as sebaceous carcinoma. The distinction of sebaceous carcinoma from benign lesions relies on histological identification of architectural or cytological features of malignancy. In this study we have assessed the diagnostic discriminatory ability of mitotic rate and immunohistochemical markers (p53, bcl-2 and p16) in a selected group of well circumscribed sebaceous neoplasms, incorporating examples of sebaceous adenoma, sebaceoma and sebaceous carcinoma. We found that mitotic rate was significantly higher in malignant lesions as compared to benign lesions, but none of the immunohistochemical markers showed a discriminatory expression pattern. In addition, we performed a mutational analysis on the same group of lesions using next generation sequencing (NGS) technology. The most commonly mutated gene was TP53, although there was no correlation between the p53 immunohistochemical results and number or type of TP53 mutation detected. CDKN2A, EGFR, CTNNB1 and KRAS were also commonly mutated across all lesions. No particular gene, mutation profile or individual mutation could be identified which directly correlated with the consensus histological diagnosis. In conclusion, within this diagnostically challenging group of lesions, mitotic activity, but not immunohistochemical labelling for p16 or bcl-2, correlates with diagnostic category. While a number of genes potentially involved in the genesis of sebaceous neoplasia were uncovered, any molecular differences between the histological diagnostic categories remain unclear.

Sebaceous carcinoma: review of the literature

BACKGROUND

Sebaceous carcinoma is an uncommon adnexal neoplasm with a documented capability for regional and distant metastasis. Traditionally, sebaceous carcinoma has been associated with high rates of recurrence after excision.

OBJECTIVE

To review the current literature on sebaceous carcinoma and detail its epidemiology, pathogenesis, clinical presentation, histopathology, diagnostic workup, treatment, and prognosis.

MATERIALS AND METHODS

Literature review using PubMed search for articles related to sebaceous carcinoma.

RESULTS

Sebaceous carcinoma typically presents as a painless pink or yellow nodule. Diagnosis requires histopathologic examination, and immunohistochemical analysis often assists in the differentiation of sebaceous carcinoma from other benign and malignant skin neoplasms. Sebaceous carcinoma should prompt a workup for Muir-Torre syndrome. Periorbital sebaceous carcinoma has an increased tendency for regional metastasis, although cancer-specific mortality rates are similar among all anatomic locations.

CONCLUSION

Surgery is the preferred treatment for local disease. Limited data suggest that Mohs micrographic surgery may provide superior clinical outcomes, but more research is needed regarding the long-term outcomes. Radiation and systemic chemotherapy are reserved for recurrent or metastatic disease.

Superficial epithelioma with sebaceous differentiation involving the eyelid: a case report

Introduction

Superficial epithelioma with sebaceous differentiation is a rare benign epithelial neoplasm. It usually involves the head, neck or the back of a middle-age person. To the best of our knowledge, two ocular cases have been reported in the literature.

Case presentation

A 46-year-old man of Italian descent, with a known history of testicular seminoma treated by orchiectomy with chemotherapy and radiotherapy, presented with a tan-colored lesion measuring 4mm in diameter in his right upper lid that had been growing over 10 months. It was clinically diagnosed as papilloma. An excisional biopsy was done. On histological examination, the lesion was a well-circumscribed and sharply demarcated epithelial tumor attached to the overlying epidermis and characterized by plate-like proliferation of basaloid to squamous cells with clusters of mature sebaceous cells and foci of ductal differentiation. After a follow-up period of 5 months, no recurrence of the lesion has been documented.

Conclusions

Superficial epithelioma with sebaceous differentiation is part of the differential diagnoses of eyelid lesions. Arguments in the literature about the correct nomenclature of superficial epithelioma with sebaceous differentiation have resulted in under-diagnosed cases. The benign histological features and the lack of recurrence support its benign nature. Although no clear association has linked superficial epithelioma with sebaceous differentiation with Muir–Torre syndrome, further clinical correlation and close follow up for patients are recommended.

Interobserver variability in the diagnosis of circumscribed sebaceous neoplasms of the skin

AIMS

Separation of sebaceous adenoma, sebaceoma and well differentiated sebaceous carcinoma is a clinically important distinction which relies on a number of subjective criteria. In routine practice we had noted significant interobserver variability in the classification of these lesions. This study sought to determine the degree of interobserver variability between general surgical pathologists and dermatopathologists in the diagnosis of well differentiated cutaneous sebaceous neoplasms.

METHODS

We circulated 61 examples of well circumscribed cutaneous sebaceous neoplasms to nine pathologists, including dermatopathologists and general surgical pathologists who were asked to submit a diagnosis for each case. Fleiss' kappa statistic was used for assessment of interobserver agreement.

RESULTS

We found that only seven cases (11%) had consensus agreement across all nine pathologists. Many cases had multiple diagnoses suggested, with three or more submitted diagnoses in 26 cases (43%), while 38 cases (62%) were diagnosed as sebaceous carcinoma by at least one pathologist. There was marked variability amongst the individual pathologists in the proportion of cases diagnosed as carcinoma, ranging from 5% to 57% of cases. Fleiss' kappa statistic for all pathologists across all diagnostic categories was 0.44, amounting to only fair to moderate agreement.

CONCLUSIONS

These data indicate that there is substantial interobserver variability in the diagnosis of well circumscribed sebaceous neoplasms. This was seen in both the separation of benign and malignant lesions, as well as in the classification of the benign entities. This interobserver variability is likely to have significant clinical implications in terms of potential for over- or under-treatment, as well as in selection of cases for mismatch repair protein evaluation.

Sebaceous neoplasia and the Muir-Torre syndrome: important connections with clinical implications

Sebaceous neoplasia comprises a spectrum ranging from benign to malignant. Proper histological identification is important for treatment, prognosis and potential association with the Muir-Torre syndrome (MTS). Our increased understanding of the significance and pathogenesis of these tumours has led to improved risk stratification, screening recommendations, and treatment of patients with an initial presentation of a sebaceous tumour. This review focuses on the diagnostic and histological features of sebaceous lesions, the MTS, and recent insights into the molecular pathogenesis of sebaceous tumours.

Sebaceous lesions and their associated syndromes: part I

Sebaceous neoplasms have long been a source of confusion to dermatologists and pathologists alike. Disagreements regarding nomenclature, classification, and management have been longstanding. Sebaceous lesions represent a broad spectrum of interesting entities that range from hamartomas, hyperplasias, and benign tumors to highly malignant neoplasms. This article discusses the clinical and pathologic features of sebaceous hyperplasia, nevus sebaceous of Jadassohn, sebaceous adenoma, seboacanthoma, sebaceous epithelioma, sebaceoma, mantleoma, basal cell carcinoma with sebaceous differentiation, sebomatricoma (sebomatrixoma), and sebaceous carcinoma. Controversies regarding these lesions will be explored, and any relationship with Muir-Torre syndrome will be discussed.

Acanthomatous superficial sebaceous hamartoma? A study of six cases with clarification of the nomenclature

The nomenclature for benign tumors with foci of sebaceous differentiation is confusing and varied. In this study, the defining histological features of six such cases are reported, all distinguished pathologically by a superficial proliferation of uniform basaloid cells containing mature sebocytes in varied proportions with attachments to the overlying epidermis. Furthermore, the unifying architecture of the cases presented supports maintenance of the original nomenclature of superficial epithelioma with sebaceous differentiation and indicates that this neoplasm is perhaps not as rare as currently believed.

Muir-Torre Syndrome: Role of the Dermatopathologist in Diagnosis

Muir-Torre syndrome (MTS) is an autosomal dominantly inherited disorder characterized by sebaceous lesions and visceral malignancies. The defect is thought to be the result of a mutation in mismatch repair genes and associated with microsatellite instability. Two cases whose diagnoses were suggested first by the dermatopathologist are discussed. The first is a 47-year-old white man who over the past 6 years developed multiple sebaceous lesions. Due to the number of sebaceous lesions and their morphology, the possible diagnosis of MTS was suggested by the dermatopathologist. Subsequently, a lesion in the right colon was found during colonoscopy that proved to be a poorly differentiated cecal adenocarcinoma. A pedigree analysis revealed other family members afflicted with multiple malignancies. Genetic testing of the colonic adenocarcinoma showed microsatellite instability. The second patient is a 50-year-old white man who underwent biopsy of a skin lesion that showed features of both a sebaceous hyperplasia and sebaceous adenoma. Because of the mixed, unusual features of the lesion, the dermatopathologist suggested the diagnosis of MTS. It was later confirmed that the patient had a history of malignancies of the colon and kidney as well as a family history significant for multiple malignant neoplasms. These cases demonstrate the important role of the dermatopathologist in alerting the clinician to the possibility of Muir-Torre syndrome when the diagnosis of a sebaceous neoplasm is made, especially when unusual histologic features are observed.

Sebaceoma and related neoplasms with sebaceous differentiation: a clinicopathologic study of 30 cases

The classification of benign sebaceous neoplasms has been challenged both by the assertion that sebaceous adenomas are really carcinomas and by difficulties in drawing the boundaries between sebaceomas and other lesions. We performed a clinicopathologic study of 30 cases of basaloid neoplasms with sebaceous differentiation, excluding cases of definite sebaceous carcinoma with severe nuclear atypia invading deep within the subcutaneous tissue and those of ocular sebaceous carcinoma. We tried to classify sebaceous neoplasms in six categories with defined histopathologic criteria. All the neoplasms were characterized by aggregations of basaloid cells admixed with sebocytes and sebaceous duct-like structures located in the dermis with or without connection to the epidermis. The categories were 1) sebaceoma (14 cases); 2) trichoblastoma with sebaceous differentiation (3 cases); 3) apocrine poroma with sebaceous differentiation (2 cases); 4) low-grade sebaceous carcinoma (6 cases); 5) sebaceous carcinoma (4 cases); and 6) basal cell carcinoma with sebaceous differentiation (1 case). The sebaceoma was further subclassified as classic type (12 cases) or verruca/seborrheic keratosis type (2 cases). Although most sebaceomas can be distinguished from other lesions, there are problematic cases. We discuss the histopathologic diagnostic problems associated with sebaceoma and also argue in favor of the concept of sebaceous adenoma.

Thomsen-Friedenreich (T) antigen: a possible tool for differentiating sebaceous carcinoma from its simulators

The Thomsen-Friedenreich (T) antigen is a cryptic glycoprotein, referred to as tumor antigen or cancer-associated antigen because it is absent or masked by some carbohydrates in normal tissues, but present in many human cancers. The latter include gastrointestinal, lung, pancreatic, mammary, and some ovarian carcinomas. Cancer cells frequently undergo incomplete glycosylation resulting in the appearance of precursor structures that normally would be absent like the case with the T antigen. T antigen can be detected by several different reagents including monoclonal antibodies and several plant lectins-e.g., Arachis hypogea (peanut agglutinin). The aim of the current study was to evaluate the expression of T antigen in sebaceous carcinoma and to compare it with its simulators. The authors studied the immunohistochemical expression of T antigen in 45 skin biopsy and excisional specimens obtained from the archives of their dermatopathology laboratories, including 8 cases of sebaceous carcinoma, 15 cases of sebaceous adenoma, 9 cases of sebaceoma, 1 case of basal cell carcinoma with sebaceous differentiation, and 12 cases of basal cell carcinoma with cytologic atypia. Sebaceous carcinoma was unique in expressing a strong, diffuse cytoplasmic T antigen reactivity (7 of 8 cases) along the immature basaloid cells and the intermediate cells. However, sebaceous adenoma, sebaceoma, and basal cell carcinomas expressed negative reaction in the basaloid cells and mild reactivity in the intermediate cells. Mature sebocytes showed a strong reaction in all cases. The authors concluded that T antigen expression may be a helpful tool in differentiating sebaceous carcinoma from other sebaceous lesions that may simulate it histologically.

Sebaceous neoplasms in Muir-Torre syndrome

A 59-year-old Japanese woman presented with two sebaceous neoplasms on the chest wall and on the left cheek. The patient had a history of ascending colon cancer, and her mother had died of gastric cancer. The histopathologic features of both sebaceous neoplasms were vaguely in accordance with those of sebaceous adenoma and sebaceoma. Based on these findings, we diagnosed the patient as having Muir-Torre syndrome. The sebaceous neoplasm on the chest wall exhibited features of a sebaceous adenoma with a unique cystic appearance, namely cystic sebaceous adenoma, which has been reported as a specific marker for Muir-Torre syndrome (MTS). However, histopathologically, both the sebaceous adenoma and sebaceoma had relatively large, vesicular or heterochromous and crowded nuclei with some pleomorphism and distinct nucleoli associated with some mitotic figures, casting doubt on their benignancy. We show that some or most benign sebaceous neoplasms in MTS might have a high potential for malignant transformation or may be well-differentiated sebaceous carcinomas with low-grade malignancy, mimicking sebaceous adenoma/sebaceoma. This results in difficulties in classification regarding sebaceous neoplasms in MTS.

Pigmented and nested sebomatricoma or seborrheic keratosis with sebaceous differentiation?

Recently, the term sebomatricoma has been proposed as the most appropriate denomination to avoid controversial and confusing terms and to encompass all benign neoplasms with sebaceous differentiation. We report on two specimens that may be interpreted as examples of two new histopathologic patterns in sebomatricoma, namely, pigmented and nested sebomatricoma, or as seborrheic keratosis with sebaceous differentiation. The first case consisted of a neoplasm composed of basaloid immature cells with features of sebaceous differentiation in the form of clusters of sebocytes and sebaceous ducts, in addition to the proliferation of dendritic melanocytes arranged as solitary units scattered through the neoplastic aggregations of immature germinative sebaceous cells. The second case, in addition to the proliferation of single dendritic melanocytes as the first case, showed well-defined nests of basaloid and heavily pigmented germinative sebaceous cells connected to the skin surface and numerous sebaceous ducts. In the first case, the pigmented nature of the lesion was the most striking histopathologic characteristic, whereas the nested pattern was remarkable in the second one. Immunohistochemical investigations demonstrated positivity of cytokeratin MNF116 in neoplastic aggregations of germinative sebaceous cells, whereas the clusters of mature sebocytes and sebaceous ducts expressed epithelial membrane antigen positivity. S-100 protein made evident the scattered dendritic melanocytes, but neoplastic cells resulted negative.