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Age / Sex : 54 / F
Chief complaint: right thigh pain and palpable mass
1) What is your impression?
Two weeks later, you can see the final diagnosis with a brief discussion of this case.
(Quiz는 quiz일 뿐이오니 답안은 한개만 보내주시기 바라오며, 복수의 답안을 보내주시는 분은 정답이 포함되어 있더라도 부득이 semi-correct answer로 처리토록 하겠습니다.)
Courtesy: 이선주(Sun Joo Lee), 인제대부산백병원(Inje University Busan Paik Hospital)
Diagnosis: Intermuscular cysticercosis
Discussion
Findings:
Ultrasonography showed an anechoic lesion of 2.8cm in
size located in the intermuscular area of the medial aspect of the right thigh.
Lesion contained tubular, folded, worm-like structures, which is suggestive of
scolex. Power Doppler demonstrated no evidence of vascularity.
MRI findings revealed about 2.6x2.4x3.8cm
sized high signal intensity mass on
T2-weighted image, showing hypointense on T1-weighted image and irregular thin
peripheral rim enhancement in the medial aspect of the right thigh between
gracilis and adductor muscles groups. Sagittal T2-weighted image demonstrated a
tubular, hypointense structure located within the lesion corresponding to the
worm-like structure seen on ultrasound.
Differential Diagnosis: Myxoma
Neurogenic tumor with cystic
degeneration
Necrotic lymph node
Abscess
Diagnosis: Intermuscular cysticercosis
Discussion:
Cysticercosis is a disease caused by encysted larvae of the
tapeworm Taenia solium, which are a pork
tapeworm and a well-known parasite in human beings. The organism has a marked
tendency to lodge in the central nervous system, subcutaneous tissue, and
muscle; less frequently, cysticerci may localize in the eyes, lungs, heart,
oral cavity, or breast. Muscular and soft tissue cysticercal involvement as a solitary lesion is a
rare disease. The muscular form of cysticercosis is generally asymptomatic and
3 different clinical manifestations are; the myalgic, myopathic and the nodular
or mass like type.
Diagnosis of cysticercosis is
often difficult and requires a high index of suspicion. Radiographs are not
helpful unless the cyst is calcified. Ultrasonography provides a useful tool in
identifying a suspected cysticercosis. One of the sonographic appearances of
cysticercosis is the cysticercus cyst with an inflammatory mass around it, as a
result of the death of the larva. The second type is an irregular cyst with
very minimal fluid on one side, indicating the leakage of fluid. The eccentric
echogenic protrusion from the wall due to the scolex is not seen within the
cyst. It may be due to escape of the scolex outside the cyst or partial
collapse of the cyst. The third appearance is a large irregular collection of
exudative fluid with the typical cysticercus cyst containing the scolex. The
fourth sonographic appearance is that of calcified cysticercosis. On MRI, typically
the cyst shows hyperintense T2W signal and hypointense T1W signal.
Post-contrast peripheral rim enhancement is also a characteristic feature of a
cysticercosis. The classic hallmark as seen on MRI is visualization of the scolex.
Treatment of intramuscular
cysticercosis is either medical or surgical therapy. Isolated skeletal muscle
or subcutaneous cysticercosis does not require specific treatment unless it is
painful.
References:
1. Sharma, P., et al., An ultrasonographic
evaluation of solitary muscular and soft tissue cysticercosis. Kathmandu Univ
Med J (KUMJ), 2010. 8(30): p.
257-60.
2. Jankharia, B.G., et al., MRI
and ultrasound in solitary muscular and soft tissue cysticercosis. Skeletal
Radiol, 2005. 34(11): p. 722-6.
3. Vijayaraghavan, S.B.,
Sonographic appearances in cysticercosis. J Ultrasound Med, 2004. 23(3): p. 423-7.
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