F13A1 and Kaposi's sarcoma: This association has been previously described in conditions such as psoriasis and Kaposi sarcoma.13,14 In the latter, the hyperactivity of dendrocytes caused by the human immunodeficiency virus infection affects the local immune response rich in mast cells, contributing to its pathogenesis.14 In LLSCC samples, the correlation between degranulated mast cells and factor XIIIa expression, albeit weak, was positive.