Rare Coexistence of Monilethrix and Trichorrhexis Nodosa in a Pediatric Patient: A Case Report.

Monilethrix is a rare genetic disorder characterized by sparse, brittle hair, primarily affecting the scalp, although it may also affect other parts of the body. Trichorrhexis nodosa (TN) is another hair shaft disorder characterized by brittle and fragile hair shafts. Concurrence of monilethrix and TN is exceedingly rare. We report a 6-year-old girl with sparse and brittle hair in the occipital and frontotemporal regions, accompanied by perifollicular papules and follicular hyperkeratosis. Hair shaft disorders and loose anagen syndrome were among the differential diagnoses. Dermoscopy revealed a beaded appearance of the hair caused by uniform elliptical nodes and internodal constriction. Additionally, light microscopy examination confirmed the presence of elliptical nodes and intermittent constrictions in the hair, along with splitting of the hair shafts exhibiting a paintbrush bristle pattern. Subsequently, the diagnosis of concurrent monilethrix and TN was made for the patient. We observed minimal clinical improvement after treatment with low-dose oral and topical minoxidil.