Dermoscopy improves diagnosis of tinea nigra: a study of 50 cases.

Background/objectives: Tinea nigra is a relatively uncommon dematiaceous fungal infection of the palms and soles, which clinically may mimic a melanocytic lesion. We sought to ascertain how frequently misdiagnosis of this infection occurred and whether the use of dermoscopy helped in its diagnosis.

Methods: Fifty consecutive cases of tinea nigra diagnosed at a dermatopathology laboratory were examined with regard to the clinical diagnosis, use of dermoscopy and the mode of management.

Results: Of the 50 cases, 21 (42.0%) were treated by shave or surgical excision. The clinical diagnosis of tinea nigra was made in five cases (10.0%) and suggested along with other diagnoses in a further two cases (4.0%). The dermatologists (n = 9) gave the correct diagnosis in four patients (44.4%), the general practitioners (n = 38) gave the correct diagnosis in one patient (2.6%) and the three surgeons involved did not give the correct diagnosis. When dermoscopy was used, in seven of 13 (53.8%) cases tinea nigra was suggested as a probable diagnosis but when dermoscopy was not used (n = 37) tinea nigra was not clinically diagnosed (P < 0.001).

Conclusions: The diagnosis of tinea nigra is significantly improved by dermoscopy, the disease should be considered as a cause of palmar or plantar pigmentation.