Track: Case Reports

Topic: Neoplasia,Carcinogensis,Tumor Biology

Abstract:

A 92-year-old male with a dermatologic history of basal and squamous cell carcinoma noted a bump on his posterior scalp, bothersome when combing his hair. A 7 mm dermal papule with central crusting was biopsied, thought to be an irritated seborrheic keratosis or pilar cyst. Histologically, the lesion was an atypical spindled cell dermal proliferation, with elongated nuclei, haphazardly arranged with occasional fascicles and desmoplastic stroma. The lesional cells were positive for GATA3, D2-40, pancytokeratin (OSCAR and AE1.3/PCK26), and p53 (overexpression) and negative for S100, WT-1, calretinin, p40, desmin, and CD68. BAP1 was retained with complete loss of MTAP and Merlin/NF2. He was diagnosed with sarcomatoid mesothelioma on left pleural biopsy five months prior, with a similar immunoprofile to this cutaneous lesion. The diagnosis of metastatic sarcomatoid mesothelioma was made. This patient had a history of occupational asbestos exposure and former smoking history, and had a multilobulated left hemithoracic pleural mass, invading two ribs and chest wall, seen on follow-up CT of a previously identified spiculated thoracic mass. The patient is currently receiving treatment with Nivolumab. Although there is no evidence of recurrence on the scalp, a new cutaneous metastasis was diagnosed on the left cheek five months later. To our knowledge, this is the fifth reported case of cutaneous metastatic sarcomatoid mesothelioma. This case is a reminder to have mesothelioma on the differential, especially in patients with asbestos exposure, and to ensure a thorough clinical history when faced with complex dermal spindled cell proliferations.

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Scott Wenson, MD