Plica Neuropathica (Plica polonica) Following Azathioprine-induced Pancytopenia

A 54-yr-old woman, on azathioprine for interstitial lung disease, developed pancytopenia and presented with sudden onset of extensive hair loss from the scalp followed overnight by appearance of elongated broad mass of uncombable matted hair which had the typical appearance of Plica neuropathica. Microscopic examination of hair clipped from the matted mass revealed irregular, nodal, superficial fractures of the hair shaft resembling Trichorrhexis nodosa and irregular ruffling of the cuticles. The areas of cuticular damage appeared dark under polarized light. Plica neuropathica following pancytopenia is unusual and the findings of hair shaft cuticular damage suggests that changes in surface characteristics of hair shafts may have led to the irreversible matting leading to development of plica along with extensive hair loss due to anagen effluvium.