Inverted follicular keratosis

Case 293   July 2011 (? P McKee)  F 52  warty nodule, cheek 

Again I thought it was an irritated seb wart with lovely squamous eddies and keratin pearls 

Case 895  22.11.13 (R. Carr)  F 89 cutaneous horn, eyebrow 

Most, including me, thought it was an irritated seb wart.  Follicular mucin. CD34-ve. 

Case 1183  5.1.15 (M. Hurt)  M 85 lesion forehead 

Most thought trichilemmoma, until –ve CD34 swung it to inverted follicular keratosis 

Case 1287   29.5.15 (R. Carr)  F 70 cheek 

Collision with seb wart.  Rather basaloid but BerEP4 –ve.  Minimal atypia against fSCC.  Ki67 quite active, as it can be in IFK and seb wart. 

Case 1911 26.9.17 (U. Sundram)  F 77 forehead 

Solid nodular variety (see 2378).  Expansile lobules arising from epidermis.  Squamous eddies and keratin pearls.  Slightly pleomorphic with evidence of invasive lower border. No mitoses. 

Case 1938  2.11.17  (IH Chaudhry)  M 53 lesion abdo 2y. 

Low-power showed poromatous architecture.  However, the cytology was not poroid, more irritated seb k with sq eddies, and differentiation was more follicular rather than ductal 

Case 2318  6.5.19 (got this one having seen 2378 below). 

Case 2378  6.8.19 (U. Sundram) M 65 forehead 

This looked like inflamed Bowen’s disease.   Head and neck, older males.  Endophytic proliferation of follicular infundibulum with squamous eddies.  Peripheral basaloid cells. 

Several patterns: wart-like; KA-like; solid nodular. 

DD:  seb wart; SCC; tricholemmoma. 

Ref:  Dermatology  2013  227: 62. 

Case 2715  2.12.20  (IH Chaudhry) F 85 cheek 

Rather fragmented.  Somewhat trichilemmal look. Squamous eddies and lymphocytic reaction.   

Case 3086 3.5.22 (U. Sundram) M 66 lesion, thigh 

Squamous eddies and lymphocytic reaction 

Case 4292  4.7.23 (U. Sundram)  M 60 lesion on face