Solitary cysticercosis affecting deltoid muscle: A rare entity

Cysticercosis is a common parasitic infection in developing countries involving the central nervous system (CNS), eye, skeletal muscle, and subcutaneous tissue. Solitary intramuscular cysticercosis without CNS involvement is a rare entity. Here, we present a case of solitary cysticercosis involving a rare muscular site without any neurologic or systemic manifestation.

Keywords: Cysticercosis, deltoid muscle, parasitic infection

Infection caused by the larval form of Taenia solium is called cysticercosis. The meninges and the eyes are the most common sites of affection followed by muscles, heart, lungs, peritoneum, and the maxillofacial region. ^[1],[2] Soft tissue and intramuscular cysticercosis are usually multiple and associated with the central nervous system (CNS). However, few cases of solitary intramuscular cysticercosis without CNS involvement have been reported. ^[3],[4]

A 33-year-old female patient presented to the surgical outpatient department (OPD) in March 2014 with a painful swelling that had been gradually increasing in size over the left deltoid muscle region for a duration of 5 months. She was a housewife and was nonvegetarian but had no history of pork consumption. On local examination, an ill-defined deep seated mass was felt deep to the deltoid muscle. The swelling was cystic in nature, freely movable, and exerted pain on pressure. The skin was normal. On physical examination, no neurological deficit or systemic abnormalities were elicited. The hematological parameters were normal. Magnetic resonance imaging (MRI) of the left arm showed rounded hyperintense lesion with identifiable hypointense nidus on T2-weighted images. Computed tomography (CT) scan of the brain was normal. The cyst was surgically excised en bloc and was sent to the microbiology department for identification. On gross examination, the cyst was 7.5 cm × 5 cm size and pearly white with milk spot (distinctly visible scolex on the arrow mark) [Figure 1]. On aspiration, a clear straw colored fluid was seen. Bacteriological culture was sterile. Histopathological examination revealed the presence of cysticercus larva. Mixed inflammatory cellular reaction was suggestive of parasitic infection [Figure 2]. The serum sample of the patient was also found positive for immunoglobulin G (IgG) ELISA (NovaTec Immunodiagnostics, Waldstra, Dietzenbach, Germany). The lesion was identified as cysticercosis. The patient was treated with albendazole (15 mg/kg/day for 14 days).

Human cysticercosis is an infection by the larval stage (cysticercus) of Taenia solium. It is commonly seen in developing countries due to overcrowding, poor sanitation, and unhygienic conditions, allowing greater contact between humans and pigs. This increases chances of fecal contamination with food and water. ^[3] Infection with the adult worm is caused due to the ingestion of inadequately cooked pork infected with encysted larvae (cysticercus). The larva develops into an adult worm in the intestinal mucosa within 5-12 weeks. Eggs and proglottids are passed in the feces, and this remains the source of infection for pigs and humans. Oncosphere from the ingested egg released in the presence of gastric secretions penetrates the intestinal wall to enter the mesenteric venules and reach various sites of the body. ^[5] Occasionally, humans can also get infected in the same way as pigs by eating food and drinking water contaminated with eggs. Muscular cysticercosis may present clinically with myalgia, pseudotumor, or pseudohypertrophy, confusing with lipomas, epidermoid cysts, granular cell tumors, neuroma, neurofibromas, pseudoganglia, sarcoma, myxoma, pyomyositis, or tuberculous lymphadenitis, etc. ^[6],[7] Solitary cysticercosis is difficult to diagnose because of the lack of other systemic manifestations. As per the world literature review, this is the first report of cysticercosis affecting the deltoid muscle. Definite diagnosis of cysticercosis is made by radiological finding, gross morphology of the cyst with scolex, and histopathological features. Surgical removal of the cyst is indicated for localized symptomatic lesions. Medical treatment with albendazole (15 mg/kg/day for 8-28 days) and praziquantel (50-100 mg/kg/day for 15-30 days) has been recommended for neurocysticercosis and subcutaneous cysticercosis. ^[8]

Solitary myocysticercosis in developing countries should always be considered as the differential diagnosis of muscular pseudotumors. Despite negative blood picture, one should go for noninvasive radiological techniques (like MRI) to arrive at a diagnosis. A cyst of small size can be managed nonsurgically, whereas a cyst of a large size or with pressure symptoms may be surgically removed.

Source of Support: None, Conflict of Interest: None

DOI: 10.4103/1755-6783.159834

[Figure 1], [Figure 2]