Cutaneous Pseudomyiasis Associated with Psychoda sp. (Diptera: Psychodidae) in a Pediatric Patient: A Case Report from Italy

Abstract

Psychodid flies are non-parasitic insects commonly found in humid domestic environments, where larvae develop in organic matter within drains. Human pseudomyiasis caused by these flies is a rare and often neglected condition, typically involving urogenital or intestinal tracts. Most cases are reported in Southeast Asia and the Middle East, while occurrences in Europe and Africa remain uncommon. This study reports the first documented pediatric cutaneous pseudomyiasis case associated with a psychodid larva in Italy. A 4-year-old girl presented with a small (0.5 cm) subcutaneous swelling on the right arm, showing dark discoloration and a protruding structure. No pruritus or systemic symptoms were observed. A partially removed larval specimen was analyzed using morphological and molecular approaches. Morphological analysis confirmed that the specimen was a dipteran larva; however, its degraded condition precluded reliable determination of the larval instar. Molecular characterization targeting the mitochondrial cytochrome c oxidase subunit I (COI) gene assigned the specimen to the genus Psychoda (family Psychodidae). These findings are consistent with an incidental recovery of a psychodid larva and support an interpretation of pseudomyiasis rather than true myiasis. This case highlights the role of interdisciplinary collaboration between pediatricians and entomologists and a One Health approach in diagnosing unusual parasitological conditions.