Cutaneous onchocercoma

Abstract

Onchocerciasis is a common, chronic multisystem disease with dermatologic, ocular, and systemic manifestations. Although the disease is endemic in Africa, Latin America, and Yemen, imported cases have been described in the United States. The causative organism, Onchocerca volvulus, is transmitted by the bite of a black fly of the genus Simulium. There are a number of cutaneous manifestations of the disease, including onchocercomas, which are subcutaneous bundles of worms. The antiparasitic agent ivermectin is the drug of choice for both prophylaxis and treatment of active disease.

Onchocercosis Mansonella Co-Infection Presenting as a Subcutaneous Nodule in a Child

“…The disease is limited to Africa, Central America, and northern South America. It is estimated that there are 18 million cases worldwide with 17.5 million found in Africa and 600,000 visually impaired [4,5]. Nigeria is the most infected region.…”

“…O. volvulus microfilariae measure 220 to 360 mm in length and 5 to 9 mm in width. From anterior to posterior they have a cephalic space, anterior nuclei, terminal nuclei, a caudal space, and a tail with tapered point [5].…”

“…The diagnosis of O. volvulus can be made by histologic examination of a nodule by collecting skin snips from an infected area, immersing them in saline, and observing microscopically for the active microfilaria, or by using more sophisticated tests such as enzyme linked immunoabsorbent assay (ELISA) or polymerase chain reaction (PCR) [5]. O. volvulus microfilariae measure 220 to 360 mm in length and 5 to 9 mm in width.…”

Recent Updates on Onchocerciasis: Diagnosis and Treatment

“…In Africa, onchocercomata are often found over the bony prominences of the torso and hips, whereas in South America, where it is sometimes called "Robles disease" [1], the predominant strains typically produce nodules in the head and shoulders [19]. Cases of onchocercoma presenting as a breast mass [20] or as deep nodules in the pelvis [17] have been described. An angiogenic protein produced by the adult female is thought to contribute to the formation of the nodules.…”

“…Subdermal nodules called "onchocercomata," which are most easily seen over bony prominences [17], are another commonly reported manifestation of onchocerciasis. The value and reliability of verbal diagnosis by eliciting a history of nodules in areas where the disease is highly endemic have been described elsewhere [18].…”