Resident Rounds. Part III: Case Report: Temporary Traumatic Discoloration from Handling Moss-Covered Firewood

Pattern recognition remains a valuable tool in the accurate diagnosis of dermatologic disease. A comprehensive patient history and physical examination denote cornerstones of medical evaluation, and in our specialty, dermoscopy can supplement data gathering to allocate cutaneous eruptions into appropriate categories. We present a case of acute onset palmar discoloration occurring in an otherwise healthy patient. Correct diagnosis transpired in the clinical setting with tailored questioning based on careful examination and adjunct dermatoscopic evaluation.

A 53-year-old man presented with a two-week history of an asymptomatic eruption on both hands (Figures 1a and 1b). On physical examination, the palmar aspects of all digits and to a lesser extent both palms, with relative sparing of the creases, revealed numerous, discrete and coalescing, dark brown to black, smooth, focally linear, macules and patches. Dermoscopy revealed a uniform brown discoloration in the furrows of his acral skin (Figure 2). Based on the clinical and dermatoscopic findings, an exogenous etiology was favored.

Further investigation revealed that the patient extensively handled moss-covered firewood while on a camping trip the week prior. We recommended twice-daily treatment with warm water soaks for 10 minutes, subsequent pumice stone exfoliation, and application of urea 40% cream. His discoloration resolved in one month (Figure 3).

Contact with various wood species can manifest interesting dermatologic sequelae. Firewood related ailments not only may affect the palms, but also may involve the face, neck, eyelids, hands, and forearms as a result of airborne contact reactions to sawdust.¹ Noteworthy allergenic woods include cedar, pine, poplar, oak, rosewood, teak, and ebony.² Other reported wood product reactions include the following: erythema multiformelike lesions (eg contact with pao ferro wood),³ irritant dermatitis (eg Brazilian rainforest tree),⁴ photoallergic contact dermatitis (eg brosimum wood),⁵ pigmented contact dermatitis (eg, Brazilian tree dust),⁶ and lymphomatoid contact dermatitis (eg teak wood).⁷