HX07 Masao Ota (1885–1945): naevus of Ota, medical mycology and the physician–scholar

Abstract Masao Ota was a transformative figure in 20th-century dermatology whose work advanced the classification of pigmentary disorders and medical mycology. Ota trained at the University of Tokyo under Keizo Dohi, founder of modern dermatology in Japan. He held academic posts at four universities, culminating in his appointment as Director of the Dermatological Clinic at his alma mater, serving until his death from gastric cancer in 1945. Ota’s best-known dermatological contribution was his 1938 description of nevus fuscocaeruleus ophthalmomaxillaris, later widely known as naevus of Ota. Through systematic clinical observation, he delineated a stable dermal pigmentation disorder frequently observed in Japanese patients, and distinguished it from other facial pigmented lesions at a time when such conditions were often grouped under broad and poorly differentiated categories. His work anticipated modern dermatological approaches to pigmentary disease in skin of colour. Ota’s contributions to mycology include a published work proposing that certain cases of pompholyx could represent dermatophytosis, extending clinicmycological reasoning to vesicular eruptions of the hands and feet. He identified a distinct dermatophyte, Microsporum ferrugineum Ota, later Grubyella ferruginea, an organism of particular regional importance in East Asian tinea infections. He advanced his knowledge with training at French medical institutions under Raymond Sabouraud, and later Emile Brumpt. In collaboration with Maurice Langeron, he produced the Nouvelle Classification des Dermatophytes in 1923, contributing to an early morphology-based system of dermatophyte taxonomy. Beyond medicine, writing under the name Mokutaro Kinoshita, Ota was widely recognized as a poet, novelist and cultural intellectual. He founded the Pan-no-kai, a Tokyo modernist circle of writers and artists who fostered engagement with Western artistic modernism. Masao Ota exemplifies the physician–scholar whose scientific innovation and cultural leadership widened the intellectual boundaries of modern dermatology, reflecting his own conviction that ‘the consequence of both science and art is global and humanitarian’.