Metastatic pleomorphic dermal sarcoma: an uncommon skin tumour

A 69-year-old Caucasian male was referred to our department with a 3-month history of an enlarging, asymptomatic nodule on his forehead. Examination revealed a 15mm, shiny, erythematous nodule with no associated lymphadenopathy. Further examination was unremarkable. Excision biopsy with a 4mm peripheral surgical margin revealed a dermal-based atypical spindle cell tumour extending from the dermo-epidermal junction to the deep subcutaneous adipose tissue. There was no evidence of tumour necrosis, lymphovascular invasion or perineural infiltration. No expression of cytokeratins, S100, desmin, or CD34 immunohistochemical markers was found, but there was positive expression of CD10. The histological margins were clear by 2mm peripherally and 1.2mm deep. Histopathological and immunohistochemical findings were consistent with the diagnosis of pleomorphic dermal sarcoma (Figure 1). The patient was followed up 3-monthly in a dedicated cutaneous sarcoma clinic. Six months after excision of the primary lesion, a new 5mm papule appeared on the excision scar (Figure 2). Repeat excision revealed recurrent pleomorphic dermal sarcoma with clear margins. The multidisciplinary team consensus was to treat this further with local adjuvant radiotherapy following a staging CT scan. At 7 months, staging CT revealed a new discrete nodule in the left lower lobe of the lung. CT-guided biopsy confirmed a CD10 positive spindle cell tumour consistent with metastatic pleomorphic dermal sarcoma. The patient subsequently died from pneumonia at 11 months following diagnosis, having been too unwell for palliative chemotherapy