[Atypical myrmecia--on the importance of the anatomical site of HPVs-infection as a morphological factor].

An 11-year-old Japanese girl developed a horny tumor branching into three parts in the fourth interdigital fold of the left hand; histologically it had numerous eosinophilic granular inclusion bodies. A histological diagnosis of myrmecia was made, which was further confirmed by the demonstration of human papillomavirus type 1 (HPV-1) by the in situ hybridization method. However, the clinical picture did not resemble the so-called myrmecia. A review of other atypical cases of myrmecia on areas other than the palms and soles may indicate the role of topical factors in determining the shape of viral warts. The concept of myrmecia should be revised in view of the additional information that there is histological heterogeneity in the cytoplasmic inclusion bodies, which are the basis of the definition of myrmecia.