A rare case of metastatic basal cell carcinoma

Abstract

Background: Basal cell carcinoma (BCC) is relatively uncommon in Malaysia with non-melanomatous skin cancer being the 12^th most common malignancy in Malaysia.Metastatic basal cell carcinoma (MBCC) is extremely rare and the incidence is estimated to be 0.0028% to 0.55% among all BCC. We report a case of MBCC with a summary of clinical and histopathology findings; and the management. Case presentation: A 69-year-old Chinese man, presented with a left wrist mass for 4 years. The mass was on the dorsal surface of the wrist, ulcerated, and measured 15 x 10cm. The tumour size was 2.5 × 8.6 × 10cm on MRI, extending into the extensor digitorum tendons and possible invasion into the lumbricals. He underwent wide excision of the mass, decorticotomy of left 3^rd to 5^th metacarpal bones and amputation of 2^nd metacarpal bone. Histopathological examination showed BCC involving whole skin thickness invading the subcutaneous fat but sparing the underlying tissues, resections margins were clear, maximal diameter was 11.5 cm. The tumour was staged as pT2N0M0. After 18 months, he developed an 8 × 10cm left axillary mass which was fungating and bleeding. CT scan also showed multiple lung metastases. Repeat biopsy of the left axillary mass showed BCC with similar appearance as the previous histopathology examination. Radiotherapy to the left axilla was given (65 Gray in 30 fractions) for local control as the tumour was bleeding profusely. Discussion: A review by Wysong et al. for 194 cases of MBCC suggests that its prognosis remains poor over the past 30 years, with the median overall survival of 10 months from diagnosis despite the introduction of systemic chemotherapy and radiotherapy. Most common metastatic sites are the regional lymph nodes, lungs and bone. Large lesions (particularly those over 10 cm²) and tumours that invade deep structures, such as cartilage, skeletal muscle, or bone, are most likely to metastasize. Perineural invasion, aggressive histologic growth patterns, and long-standing lesions are additional risk factors for metastasis. Conclusion: MBCC is a rare entity. Its management is mainly guided by limited case series. In this case, radiotherapy provided palliation of local symptoms.