Extraneural cysticercosis mimicking soft-tissue tumors: a case report from a low-resource setting

Abstract

Introduction and importance:

Extraneural cysticercosis (ECC), caused by the larval stage of Taenia solium, is a major diagnostic challenge in endemic regions such as sub-Saharan Africa. ECC frequently presents as a nonspecific, solitary soft-tissue mass, easily mimicking benign tumors and leading to delayed management. This case series highlights the varied clinical spectrum of ECC in western Uganda, following the SCARE criteria.

Case presentation:

We report two clinically distinct cases of ECC at demographic extremes: a 6-year-old male with an acute intramuscular mass in the rectus abdominis, and a 65-year-old female with a 7-year history of a subcutaneous chest wall mass, both of which were clinically indistinguishable from benign tumors. Definitive diagnoses were established in both cases by histopathological examination of surgically excised specimens, which revealed the characteristic Cysticercus cellulosae scolex. Complete surgical excision was curative.

Clinical discussion:

These cases underscore the diagnostic difficulty of ECC across disparate age groups (pediatric and elderly) and varying chronicity (2 weeks vs. 7 years). The first case highlighted the risk of systemic dissemination; the second demonstrated the fibrotic burnout stage. Both cases confirm histopathology as the gold standard for definitive diagnosis, particularly in resource-limited settings where advanced diagnostics are often inaccessible.

Conclusion:

ECC must remain a key differential diagnosis for any unexplained soft tissue mass in endemic areas. The reliance on and proficiency in histopathology are critical for definitive diagnosis. These findings serve as a public health sentinel, demanding integrated One Health strategies to interrupt the Taenia solium transmission cycle.

Background

Cysticercosis, caused by the larval stage of the pork tapeworm Taenia solium, is a significant zoonotic parasitic disease that is a leading cause of acquired epilepsy globally, particularly in developing countries^[1,2^]. Humans become infected when they accidentally ingest Taenia solium eggs, usually through contaminated food or water. The disease is perpetuated in a complex life cycle involving pigs as intermediate hosts and humans as definitive hosts^[3,4^].

HIGHLIGHTS

• Extraneural cysticercosis may present as a solitary soft-tissue pseudotumor in both pediatric and elderly patients.

• Histopathology remains the definitive diagnostic standard when clinical and imaging findings are non-specific.

• Surgically confirmed cases in endemic settings signal ongoing Taenia solium transmission and the need for strengthened One Health control measures.

The epidemiology of cysticercosis is directly tied to the practice of free-range pig farming and inadequate sanitation. It is endemic in many parts of the world, including Latin America, Asia, and sub-Saharan Africa (SSA)^[2,5,6^]. In SSA, including Uganda, the disease is a major public health issue^[7,8^]. It can affect all age groups, but its manifestations often differ; children are more prone to developing muscular or subcutaneous forms, while adults more commonly present with neurocysticercosis^[1,9^].

Following the ingestion of Taenia solium eggs, oncospheres hatch in the intestine, penetrate the gut wall, and travel via the bloodstream to various tissues, where they form a cysticercus^[10,11^]. The clinical manifestation depends on the number, size, and location of these cysts, as well as the host’s inflammatory response. While neurocysticercosis is the most severe form, causing seizures and hydrocephalus, extraneural cysticercosis (ECC) can occur in muscles, subcutaneous tissue, and the eyes^[2,8,9^]. Intramuscular and subcutaneous cysticercosis often presents as a single, painless, mobile nodule, mimicking benign tumors such as lipomas or fibromas^[5,6,12^].

Diagnosing cysticercosis can be challenging due to its varied presentations. Diagnostic methods include serological assays, such as enzyme-linked immunosorbent assay for detecting antibodies or antigens, neuroimaging (CT or MRI) for cerebral lesions, and histopathological examination of excised nodules^[2,3,5,11^]. Histopathology, which reveals the characteristic cysticercus larva with a scolex, is considered the gold standard for definitive diagnosis of extraneural forms^[2,6^]. Management strategies vary based on the location and number of cysts. Solitary, completely excised subcutaneous or intramuscular lesions may not require further antiparasitic treatment, while multiple lesions or neurocysticercosis necessitate a combination of anthelmintic drugs (e.g., albendazole and praziquantel) and corticosteroids^[2,13^]. The prognosis for ECC is generally excellent following complete excision, with a low risk of recurrence^[2,14^]. Herein, we present two cases of ECC in a young child and an elderly adult, in line with the SCARE criteria^[15^].

Case presentation

Case 1

A 6-year-old male of Ankole ethnicity from a pastoralist community in Western Uganda, a region endemic for Taenia solium, presented to the Surgical Department with a 2-week history of a painless, progressively enlarging mass on his anterior abdominal wall. There was no history of trauma, fever, or constitutional symptoms such as weight loss or night sweats. The patient’s family history was unremarkable, and a social history review confirmed that he resided in an area known for pig farming. He was a well-nourished, active child with all vital signs within normal limits.

On physical examination, a firm, oval, non-tender, intramuscular mass measuring approximately 1.5 cm × 0.7 cm was palpated within the left rectus abdominis muscle. The mass was mobile with muscle contraction, confirming its intramuscular location. A preliminary clinical diagnosis of a benign soft-tissue tumor was made, with key differential diagnoses including a desmoid tumor, a benign myoma, or a soft-tissue sarcoma. Given the uncertain etiology and the atypical location, an excisional biopsy was scheduled to obtain a definitive diagnosis.

Pre-operative laboratory tests, including a complete blood count with differential, were within normal limits. An abdominal ultrasound confirmed a well-defined, oval, hypoechoic intramuscular mass with no internal vascularity or calcifications, which further supported the benign nature of the lesion. The mass was surgically excised without complication, and the patient had an uneventful post-operative recovery.

Histopathological examination of the excised specimen revealed a single ovoid, firm, white-to-gray cystic tissue measuring 1.5 cm × 0.7 cm × 0.5 cm. The gross specimen (Fig. 1A) showed a unilocular cyst containing white, larva-like structures surrounded by a thin cystic wall (Fig. 1B). Sections stained with Hematoxylin and Eosin (H&E) showed larval forms of Cysticercus cellulosae with characteristic membranous infoldings and a scolex (Fig. 1C), findings definitively consistent with intramuscular cysticercosis. The patient received a course of oral albendazole (400 mg twice daily for 21 days) and praziquantel (50 mg/kg in three divided doses) as a prophylactic measure against potential systemic spread. He showed no signs of recurrence or systemic infection at the 1-year follow-up.

Figure 1.

Morphological features of Cysticercus cellulosae. (A) Gross appearance of a unilocular cyst. (B) Bisected cyst containing internal larval structures (arrows). (C) Histological section (H&E stain, 200×) displaying the characteristic larval morphology, including membranous infoldings (arrow).

Case 2

A 65-year-old woman of Ankole ethnicity from Western Uganda presented to the Department of Surgery with a 7-year history of a solitary, painless mass on the anterior chest wall. The mass had remained stable in size and was asymptomatic. Her past medical history was unremarkable, and she had no known risk factors for parasitic infections beyond residing in an endemic area. Her vital signs and review of systems were within normal limits.

Clinical examination revealed a single, mobile, nontender subcutaneous mass measuring approximately 3 cm × 2 cm on the lateral chest wall. The mass felt cystic and had a soft consistency. It was not fixed to the underlying muscle or skin, leading to a preliminary clinical diagnosis of a dermoid cyst or lipoma. A long-standing, stable mass in this location made a malignant process less likely. The patient opted for an excisional biopsy for a definitive diagnosis. The preoperative workup was non-contributory, with all laboratory results within normal ranges. The mass was surgically excised under local anesthesia without complication.

Gross pathological evaluation of the excised specimen revealed a single piece of gray tissue measuring 3 cm × 2 cm × 1.2 cm with a cystic area measuring 1.5 cm × 1 cm × 0.7 cm (Fig. 2A). The cut surface revealed a fibrotic encapsulation, consistent with a chronic, degenerating cyst, reflecting a long-standing host fibroblastic response to the dying larva and surrounding a unilocular cystic cavity containing white larval structures (Fig. 2B). Microscopic examination of H&E-stained sections identified larval forms of Cysticercus cellulosae with membranous infoldings, a scolex, and characteristic hooklets (Fig. 2C and D). The findings were consistent with cysticercosis. The patient was informed of the diagnosis, and due to the complete, en bloc excision of the solitary lesion, no further antiparasitic medication was deemed necessary, in line with current management guidelines for solitary, completely excised cysticercosis. She remained free of symptoms at the 1-year follow-up.

Figure 2.

Pathological features of Cysticercus cellulosae. (A) Gray tissue specimen with a cystic lesion. (B) Bisected unilocular cyst revealing a fibrotic capsule and internal larval structures (green arrows). (C and D) Histological sections (H&E stain, 200×) displaying characteristic larval morphology, including membranous infoldings (arrows in C) and a scolex with hooklets (arrow in D).

Discussion

This case report presents two clinically and epidemiologically distinct cases of ECC from an endemic region of Western Uganda. While cysticercosis is a well-documented parasitic infection in this area, the presentation as a solitary, painless soft tissue mass in pediatric and elderly patients is clinically unusual and merits discussion^[2–4,6^]. These cases highlight the importance of maintaining a high index of suspicion for cysticercosis in the differential diagnosis of soft tissue tumors, particularly in endemic areas, and underscore the critical role of histopathological diagnosis.

The first case, a 6-year-old male, is particularly noteworthy. While cysticercosis is common in children in endemic regions, it is more often associated with neurocysticercosis and seizures^[8,11^]. The presentation of a solitary, well-defined intramuscular mass, clinically mimicking a benign neoplasm, is less common. This case demonstrates the protean nature of Taenia solium larval migration and the diagnostic challenge it poses. The lesion’s painless and progressively enlarging nature led to a clinical diagnosis that necessitated surgical intervention, bypassing serological testing, which, in a resource-limited setting, may not be readily available or may have low sensitivity for a single cyst^[3,9,11^]. Serological testing is lacking in Uganda. The successful excision and subsequent prophylactic antiparasitic treatment were critical in preventing potential future systemic dissemination; this management strategy is still debated for solitary lesions but remains a consideration in high-risk patients^[2,5,14^].

The second case, a 65-year-old female, presented a distinct diagnostic challenge due to the prolonged, 7-year history of the lesion. This long-standing, stable nature pointed away from a parasitic process and more toward a benign cystic lesion such as a dermoid cyst, which was the preliminary diagnosis. This presentation contrasts with the more typical acute or subacute inflammatory response associated with a newly encysted larva^[2,4,11,12^]. The extensive fibrotic component found on histopathology suggests a long-term host-parasite interaction, in which the body’s chronic inflammatory and fibrotic response has encapsulated the degenerating cyst. This phenomenon indicates a burnout stage of the infection, in which the cyst is no longer viable. For such cases, complete surgical excision is curative, and further antiparasitic therapy is often not required, aligning with recent management guidelines for solitary, completely excised lesions^[1,2,10^].

Both cases in this series illustrate the broad clinical masquerade of ECC. In Case 1, the acute, intramuscular presentation in a child prompted consideration of a desmoid tumor, benign myoma, rhabdomyoma, or soft tissue sarcoma, all of which can present as firm, non-tender, intramuscular masses in the anterior abdominal wall. In Case 2, a slow-growing, soft, subcutaneous mass on the chest wall present for 7 years closely resembled a lipoma, dermoid cyst, or epidermal inclusion cyst, the most common benign subcutaneous lesions encountered in this anatomical location. A sebaceous cyst or fibroma would also enter the differential. The pre-operative clinical and ultrasound characteristics in both cases did not discriminate between these differential diagnoses and a parasitic etiology, reinforcing the indispensability of tissue examination for diagnosis in endemic settings. It was only through the pathological examination of the excised specimens that the diagnosis was confirmed, revealing the characteristic scolex and hooklets of Cysticercus cellulosae. This is especially relevant in low-resource settings like Uganda, where advanced diagnostic imaging or serological tests are not always accessible.

Finally, these cases have significant public health implications. These presentations occurred in a region where cultural practices and endemic pig farming contribute to the disease’s high prevalence^[7,8^]. While these were solitary lesions, they serve as a stark reminder of the underlying public health issue and the need for comprehensive control strategies, including health education, improved sanitation, and targeted interventions in the pig population^[2,10^].

Take away lessons

1. ECC should be considered in the differential diagnosis of solitary soft-tissue masses in endemic areas.

2. Histopathology remains the diagnostic gold standard, especially where imaging and serology are limited.

3. Management of completely excised solitary lesions is primarily surgical, with individualized adjunctive therapy.

4. These cases underscore the need for a One Health approach to interrupt Taenia solium transmission.

5. Early diagnosis helps prevent mismanagement and avoidable complications.

Strengths

Rare presentations at the extremes of age strengthen the report’s clinical relevance. The cases underscore the diagnostic value of histopathology in resource-limited settings. The findings are multidisciplinary and highlight ongoing Taenia solium transmission, supporting a One Health perspective.

Weaknesses and limitations

The main limitations were the absence of pre-operative serology and advanced imaging, and the single-center retrospective design. Occult neurocysticercosis or disseminated disease could not be excluded with certainty. The findings are limited to surgically excised mass lesions and may not be broadly generalizable. Further studies are needed to refine non-invasive diagnosis and the role of adjunctive therapy.

Conclusion

These two cases from Western Uganda highlight the diagnostic challenge of ECC when it presents as a solitary soft tissue mass in patients at different age extremes. They underscore the need for a high index of suspicion in endemic settings, where the condition may closely mimic benign tumors such as lipomas or fibromas. The cases also reinforce the central role of surgical pathology in settings where advanced diagnostics are unavailable, while emphasizing the need for accessible, non-invasive diagnostic tools and strengthened One Health measures to address ongoing Taenia solium transmission.

Ethical approval

Ethical approval was not required for publication of this case report. However, patients’ anonymity and confidentiality have been observed all along this work.

Consent

Written informed consent was obtained from the patient’s mother (case 1) and from the patient (case 2) for the publication of this case report and any accompanying images.

Sources of funding

This research received no specific grant from any funding agency in the public, commercial, or not-for-profit sectors.

Conflicts of interest disclosure

The authors declare no conflicts of interest.

Author contributions

C.M.P.: conceptualization, data curation, writing original manuscript, review and editing, validation. B.L.T.: data curation, review and editing, validation. M.K.J.L. and B.M.V.: review and editing, validation. All authors have read and agreed to the published version of the manuscript.

Research registration unique identifying number (UIN)

Not applicable.

Guarantor

Charles Malisaba Posite.

Provenance and peer review

Not applicable.

Data availability statement

The data supporting the findings of this case report are included within the article. Any additional supporting information can be made available upon reasonable request from the corresponding author.