[472] The Diagnostic Utility of Novel Sebocyte Maturation Markers ABHD5, PGRMC-1 and Perilipin in Differentiating Sebaceous Carcinoma from Basal Cell Carcinoma with Clear Cell Features

Wei-Shen Chen, Pei-Ling Chen, Jianping Li, Anne C Lind, Dongsi Lu. Washington University School of Medicine, St Louis

Background: Sebaceous carcinoma (SebCA) is an uncommon adnexal tumor that occurs predominantly in the ocular and head/neck regions. Distal metastases affect up to 25% of patients, and the overall 5 year mortality is ∼20%. Histologically, sebaceous carcinoma consists of sebocytes at varying stages of differentiation, with more differentiated sebocytes at the center of tumor nests. Depending on the degree of sebaceous differentiation, it can be difficult to distinguish SebCA from basal cell carcinoma (BCC). Ancillary markers that separate SebCA from its mimickers are limited. In this study, we sought to identify novel and reliable immunohistochemical markers of SebCA. Specifically, we sought to test if antibodies against ABHD5, PGRMC-1 and Perilipin, proteins involved in either lipogenesis or regulation of lipid synthesis, can be utilized for this purpose.
Design: Archival surgical pathology specimens were retrieved, including 25 cases with diagnosis of SebCA, 17 BCC with clear cell features (BCC-CC) or sebaceous differentiation. Immunostains were performed on FFPE sections using anti-ABHD5, PGRMC-1 and Perilipin antibodies.
Results: First, we demonstrated the distinct localization pattern of ABHD5, PGRMC-1 and Perilipin within normal sebaceous lobules. Second, we showed that ABHD5, PGRMC-1 and Perilipin can reliably differentiate SebCA from its mimickers, namely, BCC-CC. In SebCA, PGRMC-1 showed patchy/organoid distribution and highlighted early differentiating sebocytes; ABHD5 expression was markedly diminished and reduced to a dot-like pattern; and anti-Perilipin diffusely highlighted the majority of intracytoplasmic lipid storage vacuoles in SebCA. In BCC-CC, PGRMC-1, ABHD5 and Perilipin were not expressed. In tumors with sebaceous differentiation, the antibodies highlighted only the areas of sebaceous differentiation in a pattern similar to normal sebaceous lobules (Table 1).

Table 1
 SebCABCCTotal
PGRMC +202*22
PGRMC -11516
Total2117p=<.0001
Sensitivity0.95  
Specificity0.88  
    
Perilipin +202*22
Perilipin -21517
Total2217p=<.0001
Sensitivity0.91  
Specificity0.89  
    
ABHD5 +222*24
ABHD5 -31518
Total2517p=<.0001
Sensitivity0.88  
Specificity0.88  
* with bona fide sebaceous differentiation


Conclusions: PGRMC-1, ABHD5 and Perilipin highlight sebocytes at various maturation stages in sebaceous glands. These stains can successfully differentiate SebCA from BCC-CC. In addition, our data suggest that sebaceous carcinoma is a tumor with disordered sebocyte maturation and lipid synthesis.
Category: Dermatopathology

Monday, March 19, 2012 9:30 AM

Poster Session I Stowell-Orbison/Surgical Pathology/Autopsy Awards Poster Session # 81, Monday Morning

 

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