Ectopic Schistosoma mansoni Eggs Inside a Lipoma

Area of Science:

• Parasitology
• Pathology
• Histology

Background:

• Ectopic schistosomiasis, the presence of Schistosoma parasite eggs or adults outside their typical anatomical locations, is an uncommon clinical finding.
• Schistosoma mansoni typically resides in the mesenteric or vesical venous systems, with its eggs usually found in the liver or intestines.

Observation:

• This report documents the first instance of ectopic Schistosoma mansoni eggs identified within a subcutaneous lipoma.
• The lipoma was situated in an area anatomically distant from the known tissues involved in the Schistosoma life cycle.
• Crucially, the lipoma showed no discernible connection to the portal venous system or any other vascular network that could explain egg migration.

Findings:

• Histopathological examination revealed Schistosoma mansoni eggs embedded within the lipoma tissue.
• These ectopic eggs were surrounded by multinucleated giant cells and other inflammatory cells, indicating a host immune response.
• The eggs' location within the lipoma was entirely independent of the typical vascular routes (e.g., portal veins) utilized by the parasite.

Implications:

• This case expands the understanding of ectopic Schistosoma mansoni egg dissemination in humans.
• It demonstrates that S. mansoni eggs can reach extraneously distant ectopic sites without relying on conventional vascular migration pathways.
• The findings suggest that non-vascular mechanisms or extremely rare vascular routes may be involved in the aberrant migration of Schistosoma eggs.