Case 181. HPV-1 infection (myrmecia) (15 y-o M)
Excision of a nodular skin lesion on the sole
Key words : human papillomavirus, myrmecia
The wart on the sole tends to form an intradermal cystic inclusion because of pressuring.   Inward growth of the thickened keratinocytes, cytoplasmic basophilic inclusions, groundglass nuclei are diagnostic of myrmecia, caused by HPV, type 1 (HE, low power).
Large, basophilic cytoplasmic inclusions are characteristic of myrmecia. The nuclei are groundglassed in appearance (HE, high power).   Immunostaining for HPV antigen is strongly positive in the inclusion-positive nuclei. The cytoplasmic inclusions are not stained.