Scalp Histology in RAPP‐Hodgkin Syndrome

Abstract

We report unique histologic findings in scalp biopsies from two family members with Rapp‐Hodgkin syndrome. Rapp‐Hodgkin and the related AEC syndrome show a primary scarring alopecia and pili torti. The syndromes, which are related to ectodactyly, ectodermal dysplasia and cleft lip/palate syndrome, have been credited to mutations in the TP63 gene. Most notable on biopsy is a primary scarring alopecia and abnormal hair shaft shape. Calcification in the outer root sheath epithelium, the basement membrane of the lower segment and within naked hair shafts is present. Neutrophils and bacterial rods and cocci are adjacent to the hair shaft in the superior segment, associated with dilated follicular ostia. Perifollicular fibrosis is associated with a variety of inflammatory cell types, mostly lymphocytic. One sample shows interfollicular irregular psoriasiform epidermal hyperplasia with parakeratosis, compact orthokeratosis, hypergranulosis, and intraepidermal neutrophils. Follicular architecture is abnormal with abrupt and linear loss of nucleated matrical cells (B fringe of Adamson). The line of Ayber measures 0.30 mm on average. Hair shafts measure up to 0.16 mm, with variable abnormal cross sectional shape, usually square. Outer root sheath epithelium is disorganized with slight cellular pleomorphism, and the cuticle of the inner and outer root sheath is irregular in thickness.