Primary hydatid cyst of the supraspinatus muscle: Complete removal of the germinal layer and cytodiagnosis by fine‐needle aspiration

Abstract

Primary hydatid disease of the skeletal muscle without systemic involvement is rare. The purpose of this report is to document the novel clinical presentation and the interesting facets of fine-needle aspiration in a case of hydatid disease. It was a case of primary hydatid cyst of the left supraspinatus muscle in an Indian woman living in Kuwait, which was clinically diagnosed as a lipoma. Fine-needle aspiration (FNA) yielded 2 ml of clear fluid with white particulate material. The cytocentrifuged smears prepared from the aspirated fluid showed many scolices, occasional laminated cyst wall fragments and numerous hooklets. The laminated cyst wall and scolices were PAS positive. Trichrome staining imparted a demon-head-like appearance to the scolices. The cytodiagnosis of hydatid cyst was corroborated by histopathological examination of an excised whitish membrane and an irregular cystic fragment, which showed parallel laminations without germinal layer, and skeletal muscle with granulomas and a dense eosinophilic infiltration, respectively. Quantitative serological (indirect hemagglutination) test on blood sample collected 9 days after the excision of the cyst showed insignificant antibody titer to Echinococcus sp. and after 6 weeks the antibodies were completely absent. CT scan of the chest and abdomen performed 7 weeks after removal of cyst showed no evidence of visceral hydatid cyst.

Cytomorphologic features of echinococcal cysts

“…Many other studies in the literature have also demonstrated the rarity of post aspiration complications. Therefore, FNA is still considered as a safe diagnostic procedure for echinococcal cysts, especially when used with caution including having anti‐anaphylaxis therapy readily available . There were no complications observed in either of our cases.…”

“…Although it is a rare disease in the United States (<1 case per million), echinococcosis (hydatid disease) is a zoonotic infection endemic to several regions throughout the world, particularly in areas where sheep or cattle‐raising is prevalent, including Australia, New Zealand, Middle East, South America, parts of North America, and countries bordering the Mediterranean . Both patients presented in this report were exposed to the parasites either by traveling to or emigrating from the above areas.…”

“…However, when inflammation becomes abundant and the pathognomonic evidence of hydatid cyst is scant, it may be mistaken for an abscess. Hydatid cysts have also been reported being misdiagnosed as branchial cyst and benign cystic lesion, not otherwise specified . Therefore, a diligent search for protoscolices and hooklets is crucial, especially in a markedly inflamed cystic lesion of the liver or lung.…”

Fine Needle Aspiration Cytology of Hepatic Hydatid Cyst: A Case Study

“…FNAC appears to be a safe and useful method in the diagnosis of hydatid cyst, although arguments regarding this issue persist 13. Cytologic diagnosis of hydatid cysts has been reported in the lung,14 omentum,15 muscle,16 soft tissue,10,12 brain,17 orbit,18 and joints 11…”

Cytology of hydatid cyst mimicking intra‐abdominal sarcoma, diagnosed by fine‐needle aspiration

“…There are some who defend avoiding FNA due to risks such as anaphylaxis and contamination. However, there are articles in the literature which have highlighted its supporting role for making a diagnosis …”