Trichoscopy in the Differential Diagnosis of Pseudonits

Aim: The purpose of the study was to describe the trichoscopic features of pseudonits and to assess the usefulness of trichoscopy in their differential diagnosis. Methods: A retrospective study was performed on those patients seen for the suspicion of head or pubic lice and who underwent trichoscopy with polarized light at ×10 magnification for a more accurate diagnosis. Forty-two patients (28 males/14 females, mean age: 34.5 years, range: 7-59) were evaluated. Results: In 30 cases, trichoscopy confirmed the suspicion of head (24 cases) or pubic (6 cases) lice, whereas in 12 cases it allowed for a final diagnosis of seborrheic dermatitis (5 cases), hair casts (3 cases), trichobacteriosis (2 cases), white piedra (1 case), and trichorrhexis nodosa (1 case), by showing different types of pseudonits. Conclusion: Hair examination using trichoscopy in routine clinical practice may provide useful information for the correct diagnosis, ranging from common head and pubic lice infestations to rarer shaft abnormalities. Differentiating pseudonits from nits is essential to make the correct diagnosis in order to prevent unnecessary treatment, anxiety, and/or embarrassment.