“When a Lump Is Not Just a Lump: Diagnostic Challenges in Chronic Elbow Mass Revealing Rare Nocardial Infection”

Introduction

Chronic post-traumatic soft tissue swellings may mimic benign, granulomatous, or neoplastic conditions, often resulting in delayed diagnosis and prolonged non-healing lesions. Musculoskeletal nocardiosis is exceptionally rare in immunocompetent individuals and frequently presents with non-specific clinical and radiological findings. This case highlights the diagnostic importance of multidisciplinary collaboration in identifying rare soft tissue infections.

Methods

An 18-year-old male presented with a three-year history of an intermittently discharging swelling over the medial aspect of the right elbow following a pedestrian-versus-motorcycle injury without fracture. Clinical examination, magnetic resonance imaging (MRI), surgical excision, histopathological analysis, special staining, and microbiological tissue culture were undertaken for diagnosis and management.

Results

Clinical examination demonstrated a firm mobile subcutaneous lesion over the medial epicondyle with preserved elbow movement and no neurovascular deficit. MRI demonstrated a chronic heterogeneous soft tissue lesion with non-specific features suggestive of chronic inflammatory or granulomatous pathology. Elective surgical excision was performed for definitive diagnosis and treatment.

Histopathological examination demonstrated acute-on-chronic inflammatory infiltrates, abscess formation, actinomycotic-like colonies, and prominent Splendore-Hoeppli phenomenon. Gram, Gomori methenamine silver, and Wade-Fite stains identified filamentous organisms favouring nocardial infection. Tissue cultures subsequently confirmed Nocardia otitidiscaviarum.

Following multidisciplinary discussion between orthopaedic surgery, histopathology, and microbiology teams, the patient commenced prolonged co-trimoxazole therapy for 12 weeks with weekly monitoring of full blood counts and liver function tests. Follow-up demonstrated satisfactory wound healing, preserved upper limb function, and progressive clinical improvement.

Conclusions

Persistent post-traumatic discharging soft tissue lesions with atypical imaging findings should prompt consideration of nocardial infection. Early multidisciplinary integration of radiological, histopathological, microbiological, and surgical findings is essential for timely diagnosis and appropriate long-term antimicrobial management.