A rare case of inverted follicular keratosis on the knee

Inverted follicular keratosis (IFK) is a benign tumor of the follicular infundibulum, typically seen in elderly males on the face. Its occurrence in young patients or on extremities like the knee is extremely rare and often misdiagnosed as malignancy. Here, we present a case of an 18-year-old female with an asymptomatic plaque on the left knee, evolving from a papule to a hyperkeratotic plaque with erosions due to recurrent trauma. Histopathological examination revealed endophytic lobules of squamous epithelium with numerous squamous eddies and no atypia. IFK at atypical sites in young patients poses diagnostic challenges. This case emphasizes biopsy in chronic, non-responsive extremity lesions.