A Case of Acquired Reactive Perforating Collagenosis Complicated with Bed Bug Bites and Scabies

<p>A 65-year-old diabetic male patient was referred to our department because of the appearance of itchy papules on his extremities that had not improved since about 2 months prior to his initial visit. He had caught and brought with him insects found in his bedroom. The insects were identied as bed bugs, and he was diagnosed with bed bug bites. He was treated with topical steroids and the bed bugs were exterminated ; however, the skin rash showed little improvement. Sarcoptes scabiei were detected on his ngers and scabies was diagnosed as a further complication. Scabies improved with administration of topical phenothrin ; however, pruritic papules remained. We examined the papules with skin biopsy. Histopathological examination revealed cup-shaped ulcers with adherent crusts and inammatory cell inltration in the dermis, and trans-epidermal elimination of collagen bers in some areas, leading to a diagnosis of acquired reactive perforating collagenosis (ARPC). After thorough eradication of bed bugs with insecticides and topical steroids combined with excimer light irradiation, the eruptions were markedly improved. Cases with bed bug bites are on the increase in Japan and continue to spread. If the patient is diagnosed with unexplained insect bites,the possibility of bed bug bites should be considered. The pathogenesis of ARPC is still largely unknown, but it is thought to be a complex condition with changes due to comorbidities. Insect bites with severe itching, as in the present case, may be a trigger for ARPC. It is desirable to treat not only the skin rash but also to take measures against insect bites and provide patient guidance. Skin Research, 22 : 303-308, 2023 </p>