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Sebaceous carcinoma is a rare cutaneous malignancy which is typically regarded as relatively aggressive and has traditionally been subdivided into periorbital or extraorbital tumours. We conducted a retrospective review of all cases of sebaceous carcinoma reported to the Western Australian Cancer Registry between 1987 and May 2019. The incidence of sebaceous carcinoma in Western Australia has increased over the last three decades, with extraorbital tumours being much more common than periorbital tumours. Very few sebaceous carcinomas have led directly to the death of patients; however, adverse outcomes were more likely with periorbital tumours, in particular local recurrence and the need for major surgical intervention. [ABSTRACT FROM AUTHOR]

This case highlights the successful use of pembrolizumab for neoadjuvant treatment of MMR‐deficient sebaceous carcinoma of bilateral eyelids to reduce tumour burden allowing smaller defect post‐Mohs surgery and better reconstructive outcome. Microsatellite stability, tumour mutational burden and PD‐L1 expression are important prognostic factors to be considered for the use of neoadjuvant pembrolizumab. Further studies are needed to determine if neoadjuvant pembrolizumab consistently improves surgical and cosmetic outcomes and reduces local recurrence and metastasis. [ABSTRACT FROM AUTHOR]

Cutaneous sebaceous carcinoma occurs almost exclusively on the head and neck and has a significant propensity for recurrence and metastasis. It is easily mistaken for benign conditions, resulting in inappropriate management. Thus, it is important to maintain a high index of suspicion. Despite previous reports, sebaceous carcinoma may occur with similar frequency in Asians and whites. Recent genetic data suggest there are multiple mutational groups of sebaceous carcinoma, paving the way for targeted treatment. After a diagnosis, investigations for staging and for Muir–Torre syndrome should be considered. The available evidence on the treatment options for sebaceous carcinoma is discussed, and specific recommendations for management are made. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

We present a 37-year-old woman who underwent extensive facial surgery for removal of multiple eruptive squamous cell carcinoma ( SCC)-like lesions resembling invasive SCC histologically. The patient's mother had undergone numerous surgical procedures and radiotherapy for facial SCC. A review of the histology and immunohistochemistry for DNA mismatch repair proteins excluded Muir- Torre syndrome. A diagnosis of Ferguson- Smith disease (or multiple self-healing squamous epitheliomata) was suspected. Blood was sent for DNA analysis. Twelve months later, mutations of the TGFBR1 gene were demonstrated in 18 families (67 individuals) with Ferguson- Smith disease; among whom our patient and her mother were family 11. [ABSTRACT FROM AUTHOR]

Reticulated acanthoma with sebaceous differentiation ( RASD) represents a rare benign cutaneous epithelial neoplasm with sebaceous differentiation. There has been much speculation about the relationship between RASD and Muir- Torre syndrome ( MTS). We report a 53 year-old man who presented with RASD in addition to a prior history of sebaceous adenomas. Immunohistochemically, the tumour cells in the RASD and sebaceous adenomas showed a significantly reduced MSH6 protein expression, whereas there was no loss of MLH1, MSH2 and PMS2. This benign neoplasm, which can be mistaken for various other cutaneous lesions with sebaceous differentiation, deserves wider recognition for its possible association with MTS. [ABSTRACT FROM AUTHOR]