a) mycosis fungoides _ _ _ _ _ _ _ _ _ _ Wrong answer ¯ ¯ ¯ ¯ ¯ ¯ ¯ ¯ ¯ ¯ b) parapsoriasis _ _ _ _ _ _ _ _ _ _ Wrong answer ¯ ¯ ¯ ¯ ¯ ¯ ¯ ¯ ¯ ¯ c) tinea corporis _ _ _ _ _ _ _ _ _ _ Correct ¯ ¯ ¯ ¯ ¯ ¯ ¯ ¯ ¯ ¯ d) extra-mammary Paget’s disease _ _ _ _ _ _ _ _ _ _ Wrong answer ¯ ¯ ¯ ¯ ¯ ¯ ¯ ¯ ¯ ¯ e) detergent allergy _ _ _ _ _ _ _ _ _ _ Wrong answer ¯ ¯ ¯ ¯ ¯ ¯ ¯ ¯ ¯ ¯ Answer and Commentary _ _ _ _ _ _ _ _ _ _ The well-defined margin and scaling make tinea corporis the best answer. A KOH examination of a scraping taken from the edge of the lesion confirms the diagnosis. Reactions to detergents are rare and are usually confined to body folds where there is better absorption. Parapsoriasis and early patch stage mycosis fungoides may occur anywhere, but are more homogeneous and lack the well-defined and expanding edge seen in this patient whose tinea was an extension from a tinea cruris. Trichophyton rubrum was isolated from both sites. Perianal Paget’s disease presents with a eczematous, well- marginated, slowly expanding plaque which has intractable itching. ¯ ¯ ¯ ¯ ¯ ¯ ¯ ¯ ¯ ¯
