Pathological differentiation of suspected cases of pentastomiasis in China.

We report nine cases of suspected pentastomiasis from China, and propose that diagnosis of this rare parasitic disease should be made aetio-pathologically, subaetio-pathologically, and presumptively. In none of our cases' lesions we could find either a whole or part of an embedded nymph; hence, no aetio-pathologic diagnosis of pentastomid infection was established. In three cases, subaetio-pathologic diagnoses of pentastomiasis were made upon the discovery of a peculiar set of relics from lesions, namely two pairs of circumoral hooks of pentastomid from lesions. In one of these three cases, an extra scissors-like image indicating a longitudinal section of a hook of the embedded pentastomid nymph, probably Linguatula serrata, was found. In the other six cases, none of the relics of the aetiological agents were found, and our diagnoses were made presumptively by a series of relatively specific pathologic features, i.e. pearly lesions over the peritoneal surface of the abdominal cavity under the serosa of the intestinal wall or under the capsules of liver and spleen. They tend to be uniquely protuberant, sometimes linked by a short thin stalk to the surface. The hyalinization and calcification of these centrally caseated granulomatous nodules tend to be concentric and targetoid in appearance. Tuberculosis, the most easily confused condition, was easily ruled out pathohistologically. We believe that there is a need for presumptive pathologic diagnosis of human pentastomid infection not only in China, but worldwide.