Abstract

Nodules of the hair shaft have a relatively limited set of differential diagnoses which includes fungal or bacterial infections (e.g., white piedra caused by Trichosporon species), pediculosis (nits), damage to the hair shaft cortex (trichorrhexis nodosa), or conditions that cause scalp scaling/flaking or peripillous sheaths (hair casts). Here we present a distinctive case of damaged stripped hair cuticles clinically mimicking white piedra in a patient with a history of weekly hair blowout treatments.  

The microscopic findings showed marked fraying and stripping of the cuticle parallel to/along the length of the entire hair shaft, which corresponded to the clinically observed adherent nodular look of “balled up” stripped cuticle. The more classically recognized pattern of acquired hair shaft damage— trichorrhexis nodosa— in which the hair cortex fibers display periodic “two brooms in opposition” splits was not observed microscopically. No adherent concretions or organisms were identified on routinely stained microscopy. PAS-fungus and GMS special stains were also negative for fungal organisms. A diagnosis of “hair cuticle damage secondary to heat or other exogenous treatment” was rendered. 

Acquired hair shaft deformities are well-known consequences of repetitive heat and chemical styling, with trichorrhexis nodosa being an observed pattern. The “balled up” cuticle fibers in our case presented a unique diagnostic challenge, as they more closely mimicked an adherent concretion clinically and formed a pathologic pattern not previously documented in the current body of literature. Awareness of this non-classic clinical and microscopic morphology can aid in accurate diagnosis of acquired nodules of the hair shaft.