Scapular swelling: “subcutaneous cysticercosis unveiled”—a case report

Abstract

Background

Cysticercosis, a parasitic infection caused by the larval stages of the pork tapeworm, Taenia solium, predominantly affects cerebral and ocular tissues. The subcutaneous manifestation of this disease is a relatively uncommon clinical occurrence. Previously very few or no cases of cysticercosis presenting as subcutaneous solitary painful swelling have been reported in the literature. In previous reports, the swelling was described as painless and not solitary.

Case presentation

We present a rare case of subcutaneous cysticercosis in an Indian female in her forties, localized over the left scapular region, exhibiting gradual enlargement over 4 weeks. The patient experienced pain and intense itching without neurological or ocular involvement. Physical examination revealed a well-defined nodular swelling measuring approximately 3.5 cm × 3 cm, painful, nonfluctuating, nonreducible, soft to firm consistency, with no attachment to the underlying muscle, observed at the inferior angle of the left scapula. The overlying skin was tense, glossy, erythematous, and indurated, with mild superficial scaling at a few places and excoriation marks around the swelling. No similar swelling was found elsewhere on the body. The rest of the systemic and physical examination was unremarkable. The clinical diagnosis included an abscess, infected sebaceous cyst, lipoma with inflamed overlying skin, and a remote possibility of subcutaneous cysticercosis. Stool examination for ova, cysts, and parasites was unremarkable. Cysticercus IgG antibody by enzyme-linked immunosorbent assay was negative. A chest X-ray and radiograph of the left scapular region were normal. Fine needle aspiration biopsy of the lesion was planned but could not be completed as the patient did not consent. Local part ultrasonography revealed a well-defined cystic area of 1.9 × 1.1 × 1.6 cm³ (anteroposterior × transverse × craniocaudal) with peripheral calcified streaks (scolex) and surrounding edema suggestive of subcutaneous cysticercosis. The diagnosis was established by the ultrasonography of the lesion suggesting features consistent with cysticercus, and later established by complete resolution after a course of albendazole. Management involved a 3-week course of albendazole and 5 days of paracetamol for pain, leading to the full resolution of swelling and symptoms. On follow-up at 1 month, the swelling had disappeared with no new swelling or symptoms.

Conclusion

Subcutaneous cysticercosis is an unusual presentation of Taenia solium infestation that requires a high index of suspicion for accurate diagnosis. This case report emphasizes the importance of considering parasitic infections in the differential diagnosis of subcutaneous nodules. Early diagnosis and appropriate management are crucial for preventing complications and improving patient outcomes.

Introduction

Human cysticercosis is a parasitic infection caused by cysticercus cellulosae, the larval stage of Taenia solium, commonly known as the pork tapeworm. Adult tapeworms are found in the small intestine of humans, the definitive host, while the larval forms are found in the skeletal muscles of pigs, the intermediate host. Cysticercosis develops when humans replace pigs in the T. solium life cycle, and the eggs must mature within the human small intestine. Autoinfection, ingestion, or inhalation of egg-contaminated food or water serves as the portal of entry for the eggs into the human small intestine. Eventually, these cysticerci spread through the intestinal wall, carried by the bloodstream to muscles, the brain, and subcutaneous tissues, leading to clinical manifestations [1]. Cysticercosis is predominantly observed in the brain and eyes, accounting for around 86% of cases [2,3,4], with the remainder mainly located in the muscles, heart, lungs, peritoneum, and breast [5,6,7,8,9]. Subcutaneous cysticercosis is a relatively rare form, posing a diagnostic challenge for clinicians. The first case of subcutaneous cysticercosis was described by Arora et al. in 1990 in India [10]. Here, we report a unique case of subcutaneous cysticercosis in a 40-year-old Indian woman presenting with swelling over the left scapular region, without any neurological or ocular involvement, highlighting the importance of considering parasitic infections in the differential diagnosis (Figs. 1, 2).

Fig. 1

Nodular swelling approximately 3.5 × 3 cm² with overlying skin tense, glossy, erythematous, and indurated with superficial scaling and excoriation marks around swelling

Fig. 2

Ultrasound showing a cyst with a scolex (white) and surrounding abscess

Case presentation

An Indian female in her forties, a teacher by profession, presented with a solitary swelling over the left scapular region for 4 weeks. She reported a gradual increase in the size of the swelling over the previous 2 weeks, associated with pain and intense itching. There was no history of fever, cough, unintentional weight loss, night sweats, or decrease in appetite. There was no history of local trauma or insect bite. She consumed a vegetarian diet. She had a past medical history of iron-deficiency anemia, most likely nutritional, that was managed with oral iron supplementation in the past. There was no other significant past medical or family history. Physical examination revealed a well-defined nodular swelling measuring approximately 3.5 cm × 3 cm, painful, nonfluctuating, nonreducible, soft to firm in consistency, with no attachment to the underlying muscle, observed at the inferior angle of the left scapula (Fig. 1). The overlying skin was tense, glossy, erythematous, and indurated, with mild superficial scaling at a few places and excoriation marks around the swelling. No similar swelling was found elsewhere on the body. The rest of the systemic and physical examination was unremarkable. The clinical diagnosis included an abscess, infected sebaceous cyst, lipoma with inflamed overlying skin, and remote possibility of subcutaneous cysticercosis.

Investigations revealed a hemoglobin level of 8.9 g% (normal: 12–16 g%) with mean corpuscular volume of 65.3 fL (normal: 80–100 fL), total leukocyte count (TLC) of 7700/mm³ (normal: 4500–11000) and differential leukocyte count with neutrophils of 60.4% (normal: 40–60%), lymphocytes 26.7% (normal: 20–40%), monocytes 7% (normal: 2–8%), and eosinophils 5.6% (normal: 1–4%). The erythrocyte sedimentation rate (ESR) was 42 mm in the first hour. Biochemical tests, including renal and liver function tests, were normal. Stool examination for ova, cysts, and parasites was unremarkable. Cysticercus immunoglobin (Ig)G antibody by enzyme-linked immunosorbent assay (ELISA) was negative. A chest X-ray and radiograph of the left scapular region were normal. Fine needle aspiration biopsy (FNAB) of the lesion was planned but could not be completed as the patient did not consent. Local part ultrasonography (Fig. 2) revealed a well-defined cystic area of 1.9 × 1.1 × 1.6 cm³ (anteroposterior × transverse × craniocaudal) with peripheral calcified streaks (scolex) and surrounding edema suggestive of subcutaneous cysticercosis. Magnetic resonance imaging (MRI) of the brain, contrast-enhanced computed tomography of the chest, abdomen, and pelvis, and plain radiographs of the upper and lower extremities, obtained to look for disseminated cysticercosis, were all normal. Thus, the diagnosis of subcutaneous cysticercosis was confirmed on the basis of ultrasound findings and complete resolution of swelling after course of albendazole. An ophthalmologic examination, including direct visualization of the parasite by fundoscopic examination, was conducted to exclude ocular cysticercosis. The patient was treated with albendazole (15 mg/kg/day) for 3 weeks and paracetamol 500 mg twice a day for 5 days, leading to the complete resolution of symptoms. On follow-up at 1 month, the swelling had disappeared with no new swelling or symptoms. Liver function tests on follow-up were normal.

Discussion

Human cysticercosis is a major health problem worldwide, particularly in Africa, Eastern Europe, Mexico, and South East Asia [11]. The perpetuation of this parasitic disease is related to poor hygiene and sanitation. It occurs only in humans after the ingestion of undercooked pork infected with cysticerci or vegetables or drinking water contaminated with Taenia solium eggs. In the life cycle of T. solium, humans are the only definitive host. The ingestion of undercooked pork containing cysticerci is the exclusive path to the development of human intestinal T. solium tapeworms [12]. There is also a high risk of infection by reverse peristalsis, resulting in internal regurgitation of the eggs into the stomach when the intestine harbors a gravid worm. The oncospheres penetrate the intestinal mucosa and develop into cysticerci after being carried to various parts of the body, including the brain, eyes, striated muscles, heart, lungs, liver, peritoneum, breast, and subcutaneous tissues [13, 14]. The clinical features vary depending on the site of larval invasion, larval load, extent of involvement, type of organ involvement, and host reaction. Symptoms may occur 5 years after infection but can appear as late as 10–30 years later [15].

Subcutaneous cysticercosis is a relatively rare form but should always be considered when evaluating subcutaneous swellings. It can be confused with other clinical entities, depending on the location of the swelling, such as lipoma, ganglion cyst, sebaceous cyst, dermoid, abscess, pyomyositis, tuberculous lymphadenitis, neuroma, sarcoma, myxoma, neurofibroma, or fat necrosis [16, 17]. The clinical features of subcutaneous cysticercosis depend on the cyst burden, location of the cyst, and host reaction. It may cause painless or painful subcutaneous nodules [18]. Our patient presented with a painful nodular/mass-like swelling. Fine-needle aspiration cytology (FNAC) or FNAB helps diagnose, but our patient did not consent. On ultrasound (USG), cysticercosis usually appears as a cyst with an eccentric echogenic scolex, as documented in our case. However, there can be variable appearances on USG [19]. Anatomical localization of the cysts can be done with computed tomography of the chest, abdomen, and pelvis. Magnetic resonance imaging of the brain can rule out neurocysticercosis, which can have various presentations such as seizures, chronic headaches, hydrocephalus, meningitis, focal neurological deficits, and death if not properly managed. Radiographs can reveal multiple calcifications in the muscles or subcutaneous tissues if the cysts are calcified [20]. Stool examination for ova and parasites may reveal concomitant intestinal parasitic infection. It has been reported that the sensitivity of serological tests is higher for patients with multiple cysts (94%) but drastically lower in patients with a single cyst (28%) or calcified cysts [13]. Albendazole and praziquantel are cysticidal drugs used for neurocysticercosis and subcutaneous cysticercosis. Steroids should be added in cases of neurocysticercosis to avoid any anaphylactic reaction, which may occur owing to the massive release of larval antigens. Although guidelines mainly published from high-income countries recommend only local treatment for subcutaneous cysticercosis, several case reports from endemic countries have used antihelminthic treatment for such cases [3, 14, 16, 21, 22].

Conclusion

Subcutaneous cysticercosis is an unusual presentation of Taenia solium infestation that requires a high index of suspicion for accurate diagnosis. Previous case reports on subcutaneous cysticercosis have typically described painless swelling, but our patient presented with painful swelling. This case report emphasizes the importance of considering parasitic infections in the differential diagnosis of subcutaneous nodules. Early diagnosis and appropriate management are crucial for preventing complications and improving patient outcomes.