Isolated anterior abdominal wall cysticercosis – A rare detection on high resolution ultrasound

Clinical History

A 3-year-old girl was brought to paediatric outpatient department of our tertiary medical centre by her mother with complaints of painless swelling in right subcostal region. There was no history of fever, trauma at the time of presentation and the child was otherwise normal for its age.

Imaging Findings

High-resolution ultrasound of the lesion revealed a well-defined ellipsoidal lesion (size~ 16.5x7.6 mm) with a cystic component and an eccentric echogenic nodule (Fig. 1 a, b) within it, suggestive of scolex in the muscular planes of the anterior abdominal wall in the right subcostal region. Hence, a diagnosis of isolated abdominal wall cysticercosis was made based on high-resolution ultrasound findings.

Discussion

Taenia solium infection is considered endemic in countries like South Asia, Brazil and Korea due to improper hygiene in rural areas [1]. Humans are the only definitive hosts while both humans and pigs can act as intermediate hosts. Feco-oral transmission is considered the most common mode of transmission. Humans often are infected by ingesting undercooked or raw pork, water or vegetables containing cysticerci larvae. The central nervous system is strongly affected by the parasite, however, involvement of soft tissues, orbit and muscles are less frequently seen. The subcutaneous and intramuscular cysticercosis usually presents as multiple, mobile, firm subcutaneous nodules with its predisposition to involve upper and lower limbs. They are often asymptomatic and about 1x2 cm in size. However, 20% of the cases may be painful and can lead to abscess formation [2]. Isolated soft tissue and muscular cysticercal involvement, per se, is very rare and clinically mimics the diagnosis of intramuscular tumours like lipoma, neuroma, neurofibroma, tubercular lymphadenitis and soft tissue myxomas. It is considered a diagnostic challenge if it presents as an isolated cysticercal lesion as in our case, due to lack of specific clinical features.

Serological examination may add to the diagnosis of cysticercosis. Enzyme-linked Immunoblot assay is more than 98% specific and sensitive in its diagnosis. But in cases of isolated subcutaneous and intramuscular cysticercal lesion, even the sensitivity of Enzyme-linked Immunoblot assay drops to 60 to 80% [3, 4]. Therefore high-resolution ultrasound is considered to play a key role in accurate diagnosis of isolated subcutaneous and intramuscular cysticercal lesions due to its peculiar ultrasound findings.

Other radiological modalities like MRI may also sometimes reveal the scolex in cases of solitary cysticercosis. CT may add to the diagnosis by depicting any calcification within it, if any. Scolices are more easily detected on ultrasound than MR imaging [5]. However, high-resolution ultrasound is still preferred because of its easy availability, cost effectiveness and ability to help making an early diagnosis.

Cestocidal agents like Albendazole or Praziquental may be used as an initial conservative treatment modality. Steriods can also be added to the treatment regimen in order to avoid some adverse reactions. It usually takes few weeks to months for a complete resolution of the lesion. However, surgical excision is considered the definitive treatment in cases of symptomatic patients and for cosmetic purposes.

Differential Diagnosis List

Final Diagnosis

Isolated abdominal wall cysticercosis

URL:	https://www.eurorad.org/case/12510
DOI:	10.1594/EURORAD/CASE.12510
ISSN:	1563-4086