Inverted follicular keratosis
L82.1 – Other seborrheic keratosis
394728005 – Inverted keratosis
Differential Diagnosis & Pitfalls
- (SCC) – IFK can resemble SCC clinically and histologically. Squamous eddies can be confused with keratin pearls seen in SCC; the absence of dysplasia rules out SCC. The well-defined basal palisading seen in IFK also makes this diagnosis less likely.
- (KA) – A central keratinous plug can be seen histologically in both IFK and KA, but the well-circumscribed borders and absence of atypical cells and infiltrative growth make this diagnosis less likely.
- – IFKs can resemble seborrheic keratoses clinically. Histologically, however, seborrheic keratoses are exophytic lesions that do not have a tendency to project inward.
- – Both IFK and verruca vulgaris are papillomatous lesions. However, squamous eddies are not present in verrucae on histology.
- – Trichilemmoma and IFK share several histologic findings, including basal palisading at the periphery of the lesion. However, squamous eddies are typically absent in trichilemmoma.