Black, hairy tongue is a disorder of curious morphology, which, although first described more than a century ago, continues to arouse interest because of its oddity and disputed origin. It is probably more common than has been generally supposed. Mild degrees of the condition doubtless pass unrecognized.
This malady may occur anywhere on the dorsum of the tongue, but in a typical example it arises in the triangular area in front of the circumvallate papillae and slopes forward as a dark fusiform mass, composed of elongated epithelial filaments, with a tendency to branching, giving the superficial impression of a tuft of hairs. The appearance has been appropriately likened to "the hair of a dog dampened by water" and "a field of corn laid low by the wind." The individual elements of the lesion, which may reach 3/4 in. (1.91 cm.) in length, represent hypertrophic filiform papillae, and the color may
GANDY DT. BLACK HAIRY TONGUEReport of a Case Cured with Superficial Roentgen Radiation. AMA Arch Derm Syphilol. 1952;65(1):97–98. doi:10.1001/archderm.1952.01530200101016