Purpose
Sebaceous adenomas (SAs) are rare, benign sebaceous gland tumors that typically manifest as yellow, circumscribed nodules on the eyelid, face and scalp. Histopathologically, these lesions are composed of multiple sebaceous lobules that vary in size, shape, and differentiation. SAs may be associated with internal malignancies, particularly gastric and colon cancer. This association, known as Muir-Torre syndrome (MTS) is caused by the autosomal dominant inheritance of defective genes encoding DNA mismatch repair proteins. The purpose of this study was to assess the prevalence of SAs and MTS, to determine the reliability of the clinical diagnosis of SAs, and to evaluate the immunohistochemical staining patterns of the DNA mismatch repair proteins MLH1 and MSH2 for a recent MTS case.
Methods
The histopathology reports from all eyelid specimens collected between 1993-2013 at the Henry C. Witelson Ocular Pathology Laboratory were evaluated to determine the number of SAs with or without associated MTS. The clinical diagnosis of each eyelid lesion was compared to the confirmed histopathological diagnosis in order to determine concordance. Immunohistochemical staining for MLH1 and MSH2 was performed for each SA.
Results
Of the 5884 eyelid specimens collected, nine were SAs (6 females, 3 males; 42-72 years old). The diagnosis of SA was clinically suspected in only one of the nine cases. MTS was discovered in one patient with an associated colon adenocarcinoma. The recognition of the eyelid SA on histopathology was the main reason for systemic investigation in this patient. Immunohistochemical staining for this case revealed positive MLH1 expression and negative MSH2 expression, confirming a diagnosis of MTS.
Conclusions
In this study, the diagnosis of eyelid SAs was rare. However, the importance of this benign eyelid tumor stems from its association with internal malignancies in Muir-Torre syndrome. For this reason, it is essential that ophthalmologists initiate a systemic work-up of all patients with eyelid SAs. To diagnose a SA, a biopsy should be sent for histopathological assessment, as the clinical impression is unreliable. Finally, immunohistochemical staining of mismatch repair proteins MLH1 and MSH2 is a valid and accessible strategy for investigating MTS.
Keywords: 526 eyelid •
638 pathology: human •
554 immunohistochemistry