title: Cutaneous paragonimiasis due to triploid Paragonimus westermani presenting as a non-migratory subcutaneous nodule: a case report.
abstract: BACKGROUND
  Paragonimiasis is a food-borne infection caused by Paragonimus parasites. The lungs and pleura are the primary sites for the infection; however, ectopic infection can occur in other organs such as skin, liver and brain. It is difficult to make a diagnosis of ectopic paragonimiasis due to an ignorance of, and unfamiliarity with the disease. We report the case of a patient with subcutaneous paragonimiasis diagnosed by histopathological analysis and serological testing.
  
  
  METHODS
  A 39-year-old Chinese immigrant woman presented with a subcutaneous nodule in her left lower back. The nodule was initially suspected of lipoma and she was followed up on without any treatment. However, it gradually indurated and the nodule was resected surgically. A magnetic resonance imaging scan revealed a polycystic lesion with inhomogeneous low or high intensity on T1- or T2-weighted images, respectively. The rim of the lesion was enhanced after contrast enhancement, but the inside did not show high-signal intensity. A histological analysis of the surgically resected specimen revealed variable-sized tubulo-cystic structures. The cyst wall showed a granulomatous change with scant eosinophilic infiltration. A number of parasite ova were observed in the necrotic tissue inside the cysts, and a parasite body with a presumed oral sucker and reproductive organ was also detected, suggesting a trematode infection. A subsequent serological examination showed a positive reaction of her serum to the Paragonimus westermani antigen. No abnormal findings were found on her chest computed tomography scan. The diagnosis of subcutaneous paragonimiasis caused by Paragonimus westermani was made.
  
  
  CONCLUSIONS
  We report a case presenting only as a non-migratory subcutaneous nodule without any pleuropulmonary lesion, which was initially suspected of lipoma but denied by magnetic resonance imaging scan results. The case was subsequently diagnosed as subcutaneous paragonimiasis from the results of histopathological analysis and serological testing.
authors.forename: Makoto
authors.initials: M
authors.lastname: Kodama
authors.forename: Mayumi
authors.initials: M
authors.lastname: Akaki
authors.forename: Hiroyuki
authors.initials: H
authors.lastname: Tanaka
authors.forename: Haruhiko
authors.initials: H
authors.lastname: Maruyama
authors.forename: Eiji
authors.initials: E
authors.lastname: Nagayasu
authors.forename: Tetsuhiro
authors.initials: T
authors.lastname: Yokouchi
authors.forename: Yasuji
authors.initials: Y
authors.lastname: Arimura
authors.affiliation: Section of Oncopathology and Regenerative Biology, Department of Pathology, Faculty of Medicine, University of Miyazaki, 5200 Kihara, Kiyotake, Miyazaki, Miyazaki 889-1692, Japan. mejina@med.miyazaki-u.ac.jp.
authors.forename: Hiroaki
authors.initials: H
authors.lastname: Kataoka
mesh_terms: D000328:Adult; D000818:Animals; D001415:Back; D003937:Diagnosis, Differential; D005260:Female; D006801:Humans; D008279:Magnetic Resonance Imaging; D010237:Paragonimiasis / Q000175:diagnosis* / Q000601:surgery*; D048492:Paragonimus westermani