Subcutaneous Basidiobolomycosis Masquerading as A Recurrent Soft-Tissue Sarcoma

Basidiobolomycosis is a rare granulomatous fungal infection caused by Basidiobolus ranarum, a member of the order Entomophthorales. The disease predominantly affects immunocompetent individuals living in tropical and subtropical regions (Sethy and Sahu, 2021; Kiruthiga et al., 2023; Mirmoosavi et al., 2023). The most common clinical form is subcutaneous basidiobolomycosis, which typically presents as a slowly progressive, firm, painless mass with well-defined borders. Due to its nonspecific presentation, the disease is frequently misdiagnosed as chronic bacterial infection or soft-tissue neoplasm, resulting in delayed diagnosis and inappropriate treatment (Hung et al., 2020; Fransiska et al., 2023). In recent years, increasing reports of gastrointestinal basidiobolomycosis have emerged, often mimicking abdominal malignancy, tuberculosis, or inflammatory bowel disease (Aljehani et al., 2022; Dhayhi et al., 2025). Definitive diagnosis relies on histopathological findings of eosinophilic granulomas with broad, sparsely septate hyphae exhibiting the Splendore–Hoeppli phenomenon, supported by fungal culture or special staining techniques (Welagedara et al., 2024). Management generally consists of systemic azole antifungal therapy, including itraconazole or voriconazole, while surgical intervention is reserved for cases with deep tissue extension or gastrointestinal involvement (Abduh et al., 2022).

This case report aims to highlight the clinical significance of basidiobolomycosis in a 37-year-old woman who was initially misdiagnosed with recurrent soft-tissue sarcoma with suspected left inguinal lymph node involvement, but was ultimately confirmed to have basidiobolomycosis based on histopathological findings and special fungal staining. This report also emphasizes the diagnostic challenges, therapeutic considerations, and the importance of including this rare fungal infection in the differential diagnosis of subcutaneous masses or lesions mimicking malignancy.

A 37-year-old woman presented with a mass in her left thigh that had been present since 2023. Initially, she noticed ill-defined swelling of the thigh musculature, within which she perceived a deep-seated enlarging mass measuring approximately 2×1 cm that exerted a pressure-like sensation on the leg. In 2024, the patient underwent surgical excision at Local Hospital, and the lesion was reported as benign. However, several months after surgery, the mass rapidly enlarged, raising suspicion of malignancy, and the patient was subsequently referred to Government Hospital. Fine-needle aspiration biopsy performed and suggested a malignant adipocytic tumor. The patient also reported pain in the affected leg during prolonged ambulation. Physical examination revealed a postoperative scar over the posterolateral aspect of the left thigh, with a poorly defined mass that was firm, irregular in surface, measuring approximately 15 × 10 cm, located intramuscularly and fixed to the surrounding tissues (Figure 1). Histopathological examination conducted on June 7^th , 2024, revealed a xanthogranuloma, while subsequent immunohistochemical analysis on October 22, 2024, demonstrated chronic inflammation with foreign-body granuloma formation.

 

 

Figure 1. A bulging mass is observed in the lateroposterior region of the left thigh.

 

The patient subsequently underwent magnetic resonance imaging (MRI) on January 15^th , 2025, which revealed a suspected malignant intramuscular mass in the left gluteus maximus muscle infiltrating the surrounding fascia and posterior subcutaneous fat. The mass was noted to encase the inferior gluteal artery, with associated perilesional subcutaneous edema. Bilateral inguinal lymphadenopathy was also observed, with the largest lymph nodes measuring approximately 1.9 cm on the right and 2.2 cm on the left (Figure 2).

 

Figure 2. MRI findings on T1-weighted, T2-weighted, and contrast-enhanced sequences (upper panels), and MRI findings on T1-weighted, diffusion-weighted imaging (DWI), and apparent diffusion coefficient (ADC) sequences (lower panels).

The patient subsequently underwent wide excision with left inguinal lymph node dissection (Figure 3). Intraoperative frozen-section evaluation of the intramuscular mass and excised lymph nodes suggested a malignant spindle mesenchymal tumor and reactive lymphoid hyperplasia, respectively.

 

Figure 3. Intraoperative findings and gross specimen following wide excision (anterior and posterior views).

 

Histopathological examination revealed chronic granulomatous inflammation consistent with basidiobolomycosis, with the closest surgical margin measuring 1 mm from the lesion. Periodic acid–Schiff (PAS) and Grocott’s methenamine silver (GMS) staining demonstrated fungal hyphae consistent with Basidiobolus species (Figure 4). Histopathological examination of the left inguinal lymph nodes revealed reactive lymphoid hyperplasia with no evidence of malignancy.

 

 

Figure 4. Histopathological findings of the surgical specimen with Periodic acid–Schiff (PAS) staining (upper panel) and Grocott’s methenamine silver (GMS) staining (lower panel). Arrow 1 indicates fungal hyphae, while arrow 2 highlights the Splendore–Hoeppli phenomenon.

 

Figure 5. Clinical appearance of the patient after surgery showing partial wound dehiscence (left) and after three months of treatment (right).

The patient subsequently received oral itraconazole at a dose of 200 mg twice daily for 12 weeks. The postoperative swelling and surgical wound, which had initially developed partial dehiscence, gradually improved and eventually healed completely (Figure 5)

Basidiobolomycosis is a rare subcutaneous fungal infection that frequently mimics neoplastic processes, particularly soft-tissue sarcoma. This subcutaneous mycosis most commonly affects children or young adult males (Nupur et al., 2019; Choudhary et al., 2024; Welagedara et al., 2024). However, the present case occurred in a 37-year-old adult woman, making it clinically noteworthy due to its rarity, although cases in female children (Sackey, Ghartey and Gyasi, 2017; Rajkiran et al., 2023) and a single case in a 41-year-old woman have also been reported (Welagedara et al., 2024).

The clinical manifestations of basidiobolomycosis typically present as a firm, progressively enlarging, painless, and fixed mass, which may closely resemble malignant tumors both clinically and radiologically. Several publications in recent years have emphasized that misdiagnosis as malignancy remains a major diagnostic challenge, particularly in cases involving subcutaneous tissues of the extremities or intra-abdominal organs. A recent review reported that approximately 37–45% of basidiobolomycosis cases were initially misdiagnosed as malignant tumors due to infiltrative mass appearances on imaging studies (Yarmahmoodi, Sheikhfendereski and Razavinejad, 2025). The clinical findings in the present case, including a large intramuscular mass with surrounding tissue infiltration and associated inguinal lymphadenopathy, were highly consistent with features commonly reported in malignant soft-tissue tumors. MRI findings further supported the suspicion of soft-tissue malignancy, reinforced by the presence of multiple enlarged lymph nodes measuring up to 1.9 cm.

The diagnosis of basidiobolomycosis remains challenging due to the absence of specific clinical features, making histopathological evaluation crucial. Characteristic findings include eosinophil-rich granulomatous inflammation accompanied by the Splendore–Hoeppli phenomenon, consisting of broad, sparsely septate hyphae demonstrated by Periodic acid–Schiff (PAS) and Grocott’s methenamine silver (GMS) staining. Recent studies have emphasized that identification of fungal hyphae using special staining is a key determinant for diagnostic confirmation, particularly when fungal culture is unavailable, and is considered a major diagnostic criterion, whereby fulfillment of a single major criterion is sufficient to establish the diagnosis of basidiobolomycosis (Pouladfar et al., 2024). In the present case, histopathological examination and special staining revealed broad, sparsely septate hyphae surrounded by eosinophilic material consistent with the Splendore–Hoeppli phenomenon, confirming Basidiobolus species infection and correcting the initial diagnosis of a malignant spindle cell tumor.

Optimal management of basidiobolomycosis generally involves a combination of surgical intervention and systemic antifungal therapy. However, recent literature consistently supports itraconazole as the first-line treatment due to its high efficacy and favorable toxicity profile. Case series and systematic reviews have reported high treatment success rates with therapy durations ranging from 8 to 16 weeks for subcutaneous basidiobolomycosis without visceral involvement (Saeed et al., 2019; Januar et al., 2021; Sethy and Sahu, 2021; Chaudhari et al., 2022). In this patient, administration of oral itraconazole at a dose of 200 mg twice daily for 12 weeks resulted in an excellent clinical response, consistent with current recommendations..

The role of aggressive surgical intervention in basidiobolomycosis remains controversial. Although limited excision may be beneficial for reducing disease burden and obtaining tissue for definitive histopathological diagnosis, several studies published within the past five years suggest that extensive surgery may increase the risk of wound dehiscence, delayed healing, and postoperative morbidity without significantly improving clinical outcomes when antifungal therapy is optimal (Hussein et al., 2021; Mirmoosavi et al., 2023). In the present case, wide excision was performed due to preoperative fine-needle aspiration biopsy findings that strongly suggested malignancy. Although postoperative wound dehiscence occurred and required a prolonged healing period, complete wound closure was ultimately achieved following initiation of antifungal therapy.

An additional notable aspect of this case was the presence of inguinal lymphadenopathy, which was initially suspected to represent metastatic disease. However, recent literature indicates that basidiobolomycosis rarely involves lymphatic spread; when lymphadenopathy is present, it is typically reactive rather than infectious or malignant. This observation aligns with reports demonstrating reactive lymphoid hyperplasia in the majority of patients, rather than fungal infiltration of lymph nodes (Mohammed et al., 2020; Kadhirvelu et al., 2023). Histopathological findings of reactive lymphoid hyperplasia in the present case further support this pattern

In conclusion, this case reinforces the importance of considering basidiobolomycosis in the differential diagnosis of soft-tissue masses that mimic sarcoma, particularly in immunocompetent patients residing in tropical regions. Comprehensive histopathological evaluation and appropriate fungal staining should be performed before undertaking aggressive surgical interventions. With timely and appropriate antifungal therapy, the prognosis of subcutaneous basidiobolomycosis is generally favorable, with a low risk of recurrence. This case serves as an important reminder that heightened diagnostic awareness is essential to prevent unnecessary invasive procedures and to ensure optimal patient management.

 

CONFLICT OF INTEREST

The authors stated that there is no conflict of interest.

 

ACKNOWLEDGEMENT

We would like to thank the Dean of the Faculty of Medicine, Airlangga University, and the Director of Dr. Soetomo General Academic Hospital

1.      Abduh, M.S. et al. (2022) ‘A Very Rare Basidiobolomycosis Case Presented with Cecal Perforation and Concomitant Hepatic Involvement in an Elderly Male Patient : A Case Study’. Available at: https://doi.org/https://doi.org/10.3390/ijerph19063412.

2.      Aljehani, S.M. et al. (2022) ‘Pediatric intussusception due to basidiobolomycosis : a case report and literature review’, BMC Pediatrics, pp. 1–5. Available at: https://doi.org/10.1186/s12887-022-03495-9.

3.      Chaudhari, D.G. et al. (2022) ‘Subcutaneous Basidiobolomycosis Treated Successfully with Oral Itraconazole : A Case Report’, pp. 105–108. Available at: https://doi.org/10.4103/idoj.IDOJ.

4.      Choudhary, R. et al. (2024) ‘Pediatric Basidiobolomycosis : An Uncommon and Misdiagnosed Entity’, pp. 817–822. Available at: https://doi.org/10.4103/idoj.idoj.

5.      Dhayhi, N.S. et al. (2025) ‘Pediatric gastrointestinal basidiobolomycosis : descriptive bicenteric retrospective study’, pp. 1–8. Available at: https://doi.org/https://doi.org/10.1038/s41598-025-13098-w.

6.      Fransiska, Y. et al. (2023) ‘Subcutaneous Basidiobolomycosis : A Rare and Underdiagnosed but Curable Fungal Infection - A Case Report’, 28(3), pp. 84–89. Available at: https://doi.org/https://dx.doi.org/10.17966/JMI.2023.28.3.84.

7.      Hung, T. et al. (2020) ‘Cases Skin and soft tissue infection caused by Basidiobolus spp . in Australia’, IDCases, 20, p. e00731. Available at: https://doi.org/10.1016/j.idcr.2020.e00731.

8.      Hussein, M.R.A. et al. (2021) ‘Primary Basidiobolomycosis of the Cecum in Immunocompetent Patients : Two Case Reports’, 14(2), pp. 116–124. Available at: https://doi.org/https://doi.org/10.14740/gr1368.

9.      Januar, R. et al. (2021) ‘A Rare Case of Basidiobolomycosis that has an Excellent Response with Itraconazole : Case Report’, IJRP.ORG, 73(1), pp. 4–10. Available at: https://doi.org/10.47119/IJRP100731320211807.

10.    Kadhirvelu, H.K. et al. (2023) ‘Subcutaneous zygomycosis in an immunocompetent patient caused by Basidiobolus ranarum’, pp. 1–5. Available at: https://doi.org/10.1136/bcr-2022-253515.

11.    Kiruthiga, K.G. et al. (2023) ‘Subcutaneous basidiobolomycosis : An unusual fungus in immuno-competent children , vindicating longer duration of anti-fungal treatment’, 8(3), pp. 175–177. Available at: https://doi.org/https://doi.org/10.18231/j.jdpo.2023.041.

12.    Mirmoosavi, S. et al. (2023) ‘Gastrointestinal basidiobolomycosis – A rare fungal infection: Challenging to diagnose yet treatable – Case report and literature review’, ELSEVIER, 32. Available at: https://doi.org/https://doi.org/10.1016/j.idcr.2023.e01802.

13.    Mohammed, O. et al. (2020) ‘Challenging Presentations of Seven Cases of Gastrointestinal Basidiobolomycosis in Sudan : Clinical Features , Histology , Imaging , and Recommendations’, pp. 2–5. Available at: https://doi.org/10.1055/s-0040-1721149.

14.    Nupur, P. et al. (2019) ‘Diagnostic Dilemma of Subcuteneous Basidiobolomycosis : A Clinicomycological Study’, 8(06), pp. 2181–2188. Available at: https://doi.org/10.20546/ijcmas.2019.806.259.

15.    Pouladfar, G. et al. (2024) ‘Navigating treatment for basidiobolomycosis : a qualitative review of 24 cases’. Available at: https://doi.org/10.1186/s12879-024-09664-8.

16.    Rajkiran, R.S. et al. (2023) ‘Medical Mycology Case Reports Basidiobolomycosis caused by a rare species - Basidiobolus meristosporus’, Medical Mycology Case Reports, 40(December 2022), pp. 25–29. Available at: https://doi.org/10.1016/j.mmcr.2023.02.006.

17.    Sackey, A., Ghartey, N. and Gyasi, R. (2017) ‘SUBCUTANEOUS BASIDIOBOLOMYCOSIS : A CASE REPORT’, 51(1), pp. 43–46. Available at: https://doi.org/10.4314/gmj.v51i1.9.

18.    Saeed, A. et al. (2019) ‘Antifungals in a case of basidiobolomycosis : role and limitations’, pp. 10–12. Available at: https://doi.org/10.1136/bcr-2019-230206.

19.    Sethy, M. and Sahu, S. (2021) ‘Basidiobolomycosis : Case Report and Literature Overview’, pp. 307–311. Available at: https://doi.org/10.4103/idoj.IDOJ.

20.    Welagedara, P. et al. (2024) ‘Body Amour of Basidiobolomycosis : A Case Report’, 5(05), pp. 4–6. Available at: https://doi.org/https://doi.org/10.38207/JMCRCS/2024/APR05050356.

Yarmahmoodi, F., Sheikhfendereski, M. and Razavinejad, S.M. (2025) ‘Unveiling basidiobolomycosis : key imaging features and clinical correlations’. Available at: https://doi.org/10.1186/s12879-025-11781-x.