Basosquamous carcinoma: treatment with Mohs micrographic surgery.

Background: Basosquamous carcinoma (BSC) is a rare tumor defined as a basal cell carcinoma (BCC) differentiating into squamous cell carcinoma (SCC). It is reported to have a high rate of recurrence with standard wide local excision. The aim of the current study was to report a large series of patients with BSC treated with Mohs micrographic surgery (MMS).
Methods: The prospective, multicenter case series included all patients in Australia treated with MMS for BSC, who were monitored by the Skin and Cancer Foundation Australia between 1993 and 2002.
Results: Most of the 178 tumors (95.6%) were located in the head and neck area. Recurrent tumors occurred in 47.8% of patients. The tumors were diagnosed initially as BCC in 87.4% and as SCC in 12.0% of patients. Perineural invasion was recorded in 7.9% of patients with data available. Most of these (69.0%) were previously recurrent tumors. Of 98 patients who completed a 5-year follow-up period after MMS, 4 (4.1%) had disease recurrence.
Conclusions: The low 5-year disease recurrence rate of BSC with MMS emphasized the importance of margin-controlled excision using MMS.