A rare case of muscular cysticercosis: Incidental discovery in a patient presenting with inguinal swelling

Abstract

Muscular cysticercosis is a rare infection caused by Taenia solium, typically identified incidentally during imaging for unrelated symptoms. This report describes the case of a 60-year-old male who presented with a 6-month history of dull abdominal pain and swelling in the left inguinal region. The abdominal pain, initially localized to the right hypochondrium, gradually radiated to the left hypochondrium, with no known triggers or alleviating factors. The left inguinal swelling was nontender, soft, and exhibited a cough impulse. The patient had a medical history of nonmuscle invasive low-grade papillary urothelial carcinoma, treated with transurethral resection of bladder tumor (TURBT) and intravesical BCG therapy. Radiological investigations, including contrast-enhanced computed tomography (CECT) of the abdomen and pelvis, revealed multiple calcified granulomas measuring 9-10 mm in the left diaphragm, bilateral intercostal muscles, left erector muscle, right psoas muscle, and bilateral gluteal and thigh muscles. These findings were consistent with muscular cysticercosis. An X-ray AP view of the bilateral upper thighs corroborated these findings, showing multiple radiopaque soft tissue lesions in the bilateral gluteal and thigh muscles. A hypodense lesion in the spleen, measuring 12 × 8 mm, was also observed, with no evidence of malignancy. This case underscores the importance of thorough diagnostic evaluation in endemic regions, where parasitic infections such as cysticercosis may present atypically. While the patient's primary complaints were not directly related to cysticercosis, the incidental findings emphasized the value of imaging in identifying and managing such conditions. Awareness and early recognition of muscular cysticercosis are crucial to prevent complications and guide appropriate management.

Background

Cysticercosis, caused by the larval stage of the tapeworm Taenia solium, is a significant parasitic disease with a global distribution but is predominantly endemic in regions with poor sanitation, where pig farming and consumption of undercooked pork are common [1]. The life cycle of T. solium involves pigs as intermediate hosts and humans as definitive hosts. Humans can inadvertently become intermediate hosts by ingesting T. solium eggs through contaminated food, water, or direct fecal-oral transmission, developing cysticerci in tissues such as the brain, skeletal muscles, eyes, and subcutaneous tissue [2,3]. Among the various forms of cysticercosis, neurocysticercosis is the most studied due to its significant impact on public health, being a leading cause of epilepsy in endemic regions [4]. In contrast, muscular cysticercosis is less frequently reported and often remains asymptomatic, discovered incidentally during imaging or surgical procedures. The pathophysiology involves the encystment of larvae in the musculature, which can result in localized inflammation, fibrosis, or calcification over time. Clinically, it may present as a painless or tender swelling, myositis, or calcified granulomas in chronic stages [5,6].

Radiological modalities play a crucial role in diagnosing muscular cysticercosis. X-rays can reveal radiopaque calcified lesions, while ultrasound and computed tomography (CT) provide detailed imaging of active and calcified cysts. Magnetic resonance imaging (MRI) is particularly valuable for differentiating cysticercosis from other soft-tissue pathologies [7]. In endemic areas, characteristic imaging findings, such as “dot-in-hole” or calcified nodules, warrant a high index of suspicion for cysticercosis [8]. Management of muscular cysticercosis depends on symptomatology. Asymptomatic cases often require no treatment, whereas symptomatic cases may benefit from antiparasitic therapy with albendazole or praziquantel, corticosteroids to mitigate inflammation, and symptomatic pain management [9,10]. Misdiagnosis can lead to unnecessary interventions, highlighting the importance of clinical awareness and accurate radiological interpretation. This report illustrates a rare case of muscular cysticercosis discovered incidentally during the evaluation of a patient with abdominal and inguinal symptoms. It underscores the significance of considering parasitic infections in endemic regions, particularly when atypical or incidental findings arise during imaging.

Case presentation

A 60-year-old male presented to the outpatient department with complaints of abdominal pain and a swelling in the left inguinal region, both persisting for the past 6 months. The abdominal pain initially began in the right hypochondrium, was insidious in onset, and progressively worsened over time. The pain was described as dull and aching, radiating to the left hypochondrium. The patient reported no aggravating or relieving factors. He also experienced intermittent episodes of vomiting but denied any association with specific food intake or other triggers.

The patient had no known history of systemic illnesses such as diabetes mellitus, tuberculosis, bronchial asthma, or hypertension. He reported a history of alcohol use but stated that he had stopped drinking a year before the presentation. His medical history included a diagnosis of nonmuscle invasive low-grade papillary urothelial carcinoma of the urinary bladder, for which he underwent transurethral resection of bladder tumor (TURBT) followed by 3 cycles of intravesical BCG therapy. There was no family history of similar complaints or significant illnesses.

On physical examination, the patient appeared well-nourished and in no apparent distress. Abdominal examination revealed a normal contour with the umbilicus midway between the xiphisternum and the symphysis pubis. There were no visible scars, pigmentation, or engorged veins. All abdominal quadrants moved symmetrically with respiration. On palpation, mild tenderness was noted in the right hypochondrium, but there were no signs of organomegaly, abdominal distension, guarding, or rigidity. Examination of the left inguinal region revealed a 3 × 2 cm swelling that was soft, nontender, and nonreducible, with a positive cough impulse. The overlying skin appeared normal without erythema, temperature changes, or visible veins. Bilateral testes were palpable and normal in size and texture.

Imaging studies were performed to further evaluate the patient's complaints. A CECT scan of the abdomen and pelvis revealed multiple calcified granulomas in the left diaphragm, bilateral intercostal muscles, left erector muscle, right psoas muscle, and bilateral gluteal and thigh muscles. Each granuloma measured approximately 9-10 mm, and the findings were consistent with muscular cysticercosis. Additionally, a hypodense lesion measuring 12 × 8 mm was identified in the spleen, though it showed no signs of malignancy Fig 1, Fig 2, Fig 3, Fig 4. The liver, gallbladder, pancreas, kidneys, and other abdominal organs were normal in size and appearance, and no lymphadenopathy was observed. The skeletal structures displayed degenerative changes likely attributable to age.

Fig 1.

Contrast enhanced CT axial section showing hyperdense soft tissue lesions in right iliac fossa (calcified granulomas).

Fig 2.

Contrast enhanced CT axial section showing hyperdense soft tissue lesions in left external oblique muscle (calcified granuloma).

Fig 3.

Contrast enhanced CT axial section showing hyperdense soft tissue lesions in bilateral gluteal musculature (calcified granulomas).

Fig 4.

Contrast enhanced CT axial section showing hyperdense soft tissue lesions in left erector spinae muscle (calcified granuloma).

An X-ray AP view of the bilateral upper thighs revealed multiple radiopaque soft tissue lesions in the bilateral gluteal and thigh muscles Fig. 5. These radiopaque densities confirmed the diagnosis of muscular cysticercosis and correlated with the findings from the CECT scan.

Fig 5.

X-ray AP view of bilateral upper thigh shows radiopaque multiple soft tissue lesions in bilateral gluteal and thigh muscles consistent with muscular cysticercosis.

The incidental finding of muscular cysticercosis in a patient being evaluated for abdominal and inguinal symptoms underscores the need for comprehensive imaging in patients from endemic regions. The case also highlights the diagnostic value of combining different imaging modalities to confirm rare presentations of parasitic infections.

Discussion

Muscular cysticercosis is an uncommon presentation of Taenia solium infection, typically overshadowed by the more clinically significant neurocysticercosis [11]. The parasite's life cycle involves humans as definitive hosts and pigs as intermediate hosts. Humans can become accidental intermediate hosts when T. solium eggs are ingested via fecal contamination of food or water, leading to larval migration and encystment in tissues [12]. The distribution of cysticercosis is influenced by socioeconomic factors, such as poor hygiene and free-range pig farming, making it endemic in several developing countries, particularly Latin America, sub-Saharan Africa, and Southeast Asia [13]. The clinical manifestations of cysticercosis depend on the site of cyst formation, the number of cysts, and the host immune response. Muscular cysticercosis accounts for a small fraction of cases, and its clinical course varies widely. It may present with myalgia, swelling, or pseudohypertrophy, but it is more frequently asymptomatic, as seen in the present case [6]. In disseminated cysticercosis, as observed in this patient, the involvement of multiple muscle groups, such as the diaphragm, gluteal muscles, and psoas, is rare and typically seen in individuals with high parasite burdens [14].

Radiological imaging is crucial for diagnosing muscular cysticercosis. CT scans are highly effective in identifying calcified cysts, particularly in chronic cases, while MRI offers superior visualization of active cysts, revealing cystic lesions with scolex and surrounding edema [15]. In this patient, CECT of the abdomen and pelvis identified multiple calcified granulomas across various muscle groups, consistent with resolved cysticercosis. The X-ray AP view of the bilateral thighs corroborated these findings, demonstrating characteristic radiopaque lesions in soft tissue. These findings align with previously documented cases where imaging was pivotal in confirming the diagnosis [16]. The differential diagnosis of such radiological findings includes myositis ossificans, metastatic calcifications, or granulomatous infections, such as tuberculosis. However, the characteristic distribution, size, and calcified appearance of the lesions, combined with the patient's epidemiological background, strongly favored a diagnosis of muscular cysticercosis [17].

Treatment of muscular cysticercosis depends on the clinical presentation. Asymptomatic cases with calcified lesions, like this one, do not require antiparasitic therapy. In symptomatic cases, antiparasitic agents such as albendazole or praziquantel are often combined with corticosteroids to reduce inflammation triggered by parasite death [18]. Surgery may be considered in cases of large cystic masses or complications such as abscess formation, although it is rarely necessary for muscular cysticercosis [11]. This patient required no specific treatment for the muscular cysticercosis, as the findings were incidental, and the lesions were calcified, indicating an inactive disease state. This case highlights several key lessons. First, it underscores the importance of considering parasitic infections in the differential diagnosis of unexplained radiological findings, particularly in patients from endemic regions. Second, it demonstrates the diagnostic value of combining imaging modalities such as CT and X-ray in detecting and characterizing muscular cysticercosis. Lastly, it emphasizes the importance of clinical correlation to avoid unnecessary interventions, as incidental findings may often represent benign or resolved infections. Awareness of muscular cysticercosis is essential among clinicians, particularly in endemic areas, as its diagnosis relies heavily on radiological findings and epidemiological context. Early recognition prevents misdiagnosis and inappropriate treatment and contributes to a better understanding of the diverse presentations of T. solium infection.

Conclusion

This case highlights the incidental discovery of muscular cysticercosis, a rare and often overlooked manifestation of Taenia solium infection, in a patient presenting with unrelated symptoms of abdominal pain and inguinal swelling. While the condition is typically asymptomatic and benign, its identification carries significant clinical relevance, particularly in endemic regions. This report underscores the value of imaging studies, such as CECT and X-rays, in diagnosing muscular cysticercosis, especially when characteristic calcified granulomas are present. It also emphasizes the importance of considering parasitic infections as differential diagnoses in patients with atypical or incidental radiological findings. Timely recognition and accurate diagnosis are essential to avoid misinterpretation of findings and to guide appropriate management. This case serves as a reminder of the diagnostic challenges of rare parasitic infections and the critical role of a comprehensive clinical and radiological evaluation in ensuring optimal patient outcomes.

Patient consent

Written informed consent was obtained from the patient for the publication of this case report.