Identical p53 gene mutation in malignant proliferating trichilemmal tumour of the scalp and small cell carcinoma of the common bile duct: the necessity for therapeutic caution?

Conflicts of interest: none declared. Sir, Malignant proliferating trichilemmal tumour (MPTT) is a rare neoplasm derived from the outer root sheath of the hair follicle. The tumour has a high metastatic rate and preferentially arises on the scalp in elderly people.1, 2 Primary small cell carcinoma (SCC) is usually seen in the lung in elderly people and SCC of organs other than the lung is extremely rare.3 We report a 32‐year‐old man who died of SCC of common bile duct (CBD) origin 1 year after combination chemotherapy and radiation therapy for primary MPTT on the scalp. A 32‐year‐old man presented with a 1‐year history of a large tumour on his scalp that had enlarged rapidly. Neither his family nor medical history was of significance. Physical examination at the first visit (day 0) showed a dome‐shaped reddish nodule with ulceration on the scalp, measuring 25 mm in diameter (Fig. 1a). Clinically, the tumour was suggestive of MPTT. A magnetic resonance imaging scan of the scalp and neck revealed a mass that had almost infiltrated the periosteum of the head and slight enlargement of the left two cervical lymph nodes, respectively. A whole‐body computed tomographic (CT) scan excluding the head and neck and a routine laboratory examination including blood tests were normal. Preoperative combination chemotherapy of intramuscular injection of peplomycin (5 mg daily) for 5 days and intravenous injection of mitomycin C (6 mg daily) for 1 day was performed. On day 15, the tumour was completely excised with wide margins and complete left neck dissection of cervical lymph nodes was also performed because of metastatic sentinel lymph nodes.