The incidence of metastatic basal cell carcinoma ranges from 0.003% to 0.55%. The 230 reported cases most often occurred in long-standing recurrent lesions and appeared in regional nodes or the lungs.
The stromal dependence of the tumor provides an explanation for the nonmetastasizing nature of basal cell carcinoma. The dense fibrous stroma of the lymph node in the case of metastatic basal cell carcinoma reported in the present study is similar to other reported cases with metastases to lymph nodes, bone, bone marrow, glands, and subcutaneous tissue.
This metastatic basal cell carcinoma demonstrated lymphatic and hematogenous dissemination to the lungs and lymph nodes. A dense accumulation of microvessels was present at the boundary of the tumor nests and dermal stroma and in the stroma surrounding the tumor in the lymph node.