Cysticercosis commonly involves central nervous system. Isolated involvement of skeletal muscles is rare. We have reported a case of cysticercosis herein presented as acute painful calf swelling, which is an extremely unusual presentation and, hence, a diagnostic challenge. The diagnosis was strongly suspected on ultrasonography and magnetic resonance imaging (MRI). The laboratory findings of peripheral eosinophilia and a positive enzyme-linked immunosorbent assay (ELISA) test for IgG antibodies against Taenia solium further supported the diagnosis. Complete clinical recovery was seen after 6 weeks of oral therapy with albendazole.
Keywords: Acute calf swelling, cysticercosis, magnetic resonance imaging, ultrasonography
|How to cite this article:
Sohoni CA, Sohoni DC. An unusual case of acute painful calf swelling. Ann Trop Med Public Health 2013;6:258-60
The larval of parasite Taenia solium is responsible for causing cysticercosis in human beings.  Although involvement of central nervous system is the commonest presentation of cysticercosis, other sites of the body are also sometimes involved.  However, cysticercosis presenting as acute painful swelling of the calf is extremely unusual  and has been described herein. An early diagnosis was made by using ultrasonography, magnetic resonance imaging (MRI), and laboratory investigations, which enabled us to treat the patient non-invasively.
A 28-year-old male presented with acute painful swelling in right calf region of 12-h duration. The patient did not have fever. There was no history of trauma or prolonged inactivity. The patient was non-diabetic, non-hypertensive, and without any other underlying comorbidities.
On examination, the right calf region was diffusely swollen, tense, and tender. No obvious redness or discoloration of the overlying skin was seen. The dorsalis pedis and posterior tibial pulses were normal. There was no selling around the ankle or knee joint.
Color Doppler study of the venous system did not show any evidence of deep vein thrombosis. However, ultrasonography of the calf region revealed a small oval cystic lesion measuring 1.2 × 0.5 cm within the superficial fibers of gastrocnemius muscle, with presence of internal echoes within the cyst [Figure 1]. Abnormal ill-defined hypoechogenicity was seen around the cystic lesion, probably representing perilesional edema. A post-contrast MRI performed for further characterization re-affirmed the intramuscular location and cystic nature of the lesion and showed faint rim enhancement of the lesion associated with moderate degree of perilesional edema [Figure 2]. A diagnosis of intramuscular cysticercus cyst was suggested. Screening MRI of brain did not reveal any evidence of neurocysticercosis.
||Figure 1: Ultrasonography reveals a small oval cystic lesion in the superficial fibers of the gastrocnemius muscle with presence of ill-defined hypoechogenicity in the surrounding area, representing edema
Click here to view
||Figure 2: MRI reveals the central area of the tiny lesion as (a) hyperintense on PDFS image, (b) hyperintense on T2-W image, (c) hypointense on T1-W image, consistent with a cystic lesion in the superficial fibers of gastrocnemius muscle. Moderate degree of perilesional edema is also seen. (d) Post-contrast image shows faint rim enhancement of the lesion
Click here to view
Blood investigations revealed a very high differential eosinophil count of 30%. The total leucocyte count was 11,000/mm 3 . The ELISA test for IgG antibodies against T. solium was positive (mean absorbance value 0.90) and, hence, the diagnosis was confirmed. The patient was treated medically with 400 mg albendazole, twice daily, for 6 weeks along with nonsteroidal anti-inflammatory drugs (NSAIDs) for initial few days for the pain and swelling to subside. The patient responded very well to this therapy and, at the end of 6 weeks, he was totally asymptomatic.
Acute painful calf swelling is a common presentation in any emergency unit. The most common causes of this condition are deep vein thrombosis, Baker’s cyst rupture, infection, and trauma. However, cysticercosis of the calf muscles is an extremely rare cause of acute painful calf swelling and, hence, is a diagnostic challenge. ,
Humans are the only definitive host and pigs are normally the intermediate hosts for T. solium. However, rarely man acts as the intermediate host and that results in cysticercosis. Humans acquire this infection by ingestion of eggs of T. solium from contaminated water and vegetables.  The eggs get lysed in the stomach and the oncospheres thus released penetrate the intestinal mucosa to enter the blood stream; they reach various organs via blood where they develop to form cysticercus cellulosae, an encysted larval form of T. solium.
The commonest site of involvement is the central nervous system.  Other less commonly affected sites are eyes, skeletal muscles, heart, subcutaneous tissue, pleura, and mucous membranes. , Isolated cysticercus cyst of skeletal muscle is rare. , Most cases of muscular cysticercosis are asymptomatic and go undetected. However, sometimes there may be release of antigens from the cyst into surrounding tissue with resultant incitation of an inflammatory process resulting in focal myositis. This is what probably happened in our patient and is known as the myalgic type of muscular cysticercosis.  The other types of presentation of muscular cysticercosis are the nodular type and the pseudohypertrophy type. 
Plain radiographs are not of much help in acute cases. Ultrasonography can suggest a diagnosis by demonstrating cystic lesion and surrounding inflammatory changes, as in our case. , MRI is the modality of choice for imaging of soft tissue cysticercosis. ,, Combining ultrasonography and MRI further increases the level of confidence in making the diagnosis. Eosinophilia is an indicator of helminthic infection. A positive IgG-ELISA for T. solium has a high degree of specificity for presence of T. solium antigen in the serum.  Thus, imaging and laboratory investigations enabled us to make a correct diagnosis of an extremely unusual entity by non-invasive means. Early and specific diagnosis meant that we could medically treat the patient successfully, without the need for any surgical intervention.
||Chatterjee KD. Helminthology. In: Chatterjee KD, editor. Parasitology. 11 th ed. Chatterjee Medical Publishers: Calcutta; 1976. p. 107-206.
||Mittal A, Das D, Iyer N, Nagaraj J, Gupta M. Masseter cysticercosis – a rare case diagnosed on ultrasound. Dentomaxillofac Radiol 2008;37:113-6.
||Patnayak R, Kalyani D, Rao SI, Prayaga A, Sundaram C, Jena A. Cysticercosis: The hidden parasite with short review of literature. Internet J Infect Dis 2007;6:1. Available from http://www.ispub.com/journal/the-internet-journal-of-infectious-diseases/volume-6-number-1/cysticercosis-the-hidden-parasite-with-short-review-of-literature.html#sthash.nT8M3cEA.dpbs. [Last accessed on 21 Nov 2012].
||Jhankaria BG, Chavhan GB, Krishnan P, Jhankaria B. MRI and ultrasound in solitary muscular and soft tissue cysticercosis. Skeletal Radiol 2005;34:722-6.
||Rangdal SS, Prabhakar S, Dhatt SS, Prakash M, Dhillon MS. Isolated muscular cysticercosis: A rare pseudotumor and diagnostic challenge, can it be treated non-operatively? A report of two cases and review of literature. JPMER 2012;46:43-8.
||Bhalla A, Sood A, Sachdev A, Varma V. Disseminated cysticercosis: A case report and review of literature. J Med Case Reports 2008;2:137.
||Sharma R, Gautam P, Kumar S, Elhence P, Bansal R, Gupta G. Isolated cysticercosis cellulosae of sternocleidomastoid muscle: A case report with review of literature. Indian J Otolaryngol Head Neck Surg 2011;63(Suppl 1):127-30.
||Goenka AH, Kumar A. Whole body MR and disseminated cysticercosis. Indian J Radiol Imaging 2011;21:157-8.
||Jakhere SG, Chemburkar VC, Yeragi BS, Bharambay HV. Imaging findings of disseminated cysticercosis with unusual involvement of spleen and pancreas. J Glob Infect Dis 2011;3:306-8.
||Sahu PS, Parija SC, Narayan SK, Kumar D. Evaluation of an IgG-ELISA strategy using Taenia solium metacestode somatic and excretory-secretory antigens for diagnosis of neurocysticercosis revealing biological stage of the larvae. Acta Trop 2009;110:38-45.
Source of Support: None, Conflict of Interest: None
[Figure 1], [Figure 2]