Adult Fasciola hepatica in the rectus abdominis muscle: a case report

BACKGROUND: Fascioliasis is a zoonotic disease in regard to public health, which is sporadically reported from different parts of the world. Adult worms infect the liver and bile ducts, but extrahepatic involvement and the development of parasitic myositis and muscle mass caused by Fasciola hepatica are uncommon and very rare. CASE PRESENTATION: A 55-year-old Iranian female presented with a history of abdominal pain, epigastric tenderness without pallor and jaundice, along with significant weight loss for the past five months. Microscopic examination of the stool did not identify adult worms or parasite eggs. Laboratory findings were almost normal, while erythrocyte sedimentation rate (ESR) was 32 mm/hour, triglyceride 330 mg/dL and eosinophil 6%. Hepatitis B surface antigen (HBsAg) and anti-Hepatitis C virus (HCV) were non-reactive, whereas Hepatitis B surface antibody (HBsAb) was 260.7 IU/L. Ultrasound of the tissue revealed a mass in the abdominal wall in the right upper quadrant. After her admission to the hospital, a flatworm emerged from the rectus abdominis muscle of the patient. Histopathological examination of the excised lesion showed parasite-induced myositis with abscess formation and a granulomatous foreign body reaction. Based on the morphological characteristics of the worm and serological assessment, the worm was identified as Fasciola hepatica. The patient was treated with triclabendazole and underwent clinical and paraclinical follow-up for 90 days. CONCLUSION: This case highlights the importance of diagnosing Fasciola hepatica in the differential diagnosis of unexplained subcutaneous or intramuscular nodules, especially in patients with a history of travel to endemic areas. The current case is one of the rarest cases of extrahepatic involvement (muscular fascioliasis) reported in Iran, a country where Fasciola infection is endemic in its northern regions.