Combing into trouble: localised acquired trichorrhexis nodosa

Trichorrhexis nodosa (TN) is a common hair shaft disorder characterised by node-like fracture points due to structural weakening. It can be congenital or acquired, with the latter often linked to physical or chemical trauma. This report presents a case of localised acquired TN in a teenage boy with asymptomatic white nodes over the parietal scalp. The condition was attributed to repetitive friction from a specific combing habit using a pocket-sized plastic-bristled comb. Trichoscopy revealed white nodules and broken shafts with a classic 'paintbrush' appearance, while light microscopy confirmed cortical fibre fraying and impending shaft fractures. This case underscores the diagnostic utility of trichoscopy and microscopy in differentiating TN from other hair shaft disorders and emphasises the importance of identifying behavioural causes. Patient education and behavioural modification, including the use of a wide-toothed comb, were key to management.