Extraocular sebaceous carcinoma of the chest wall: A case report

INTRODUCTION: Sebaceous carcinoma is a rare malignancy that is most commonly found in the head and neck region, particularly in the periocular region. Extraocular lesions are rarer, however are thought to have a higher association with Muir-Torre Syndrome, a variant of Lynch Syndrome, that affects both sebaceous glands and visceral organs. CASE PRESENTATION: Our patient was a 54 year old male with a past medical history of hypertension, stroke, and vertigo who presented to the emergency department with paresthesias concerning for a transient ischemic attack in the setting of a hypertensive emergency. After admission, the patient reported an abscess on the chest that was present for four months prior. Subsequent physical exam incidentally revealed a fungating mass located on the chest wall. The mass was noted to have central ulceration and necrosis. CLINICAL DISCUSSION: CT scan of the chest with intravenous contrast revealed that the mass did not invade the chest wall, therefore a surgical excision was performed. A final diagnosis of sebaceous carcinoma was made after microscopic examination of the resected mass. Immunohistochemistry revealed loss of expression of mismatch repair genes. The patient was lost to follow-up before any additional work up could be performed. CONCLUSION: Extraocular sebaceous carcinomas should be tested using immunohistochemistry for loss of expression of mismatch repair genes. Patients with loss of expression should be risk stratified using the Mayo Muir-Torre risk score to determine if they should undergo germline genetic testing for Lynch Syndrome. Patients with issues in adherence represent a unique diagnostic challenge in potentially evolving diseases.