A Case of Atypical Actinomycosis: A Diagnostic Conundrum in Lower Limb Pathology

Actinomycosis is a rare bacterial infection known for its chronic, indolent course and diverse clinical presentations. Diagnosis can be more challenging without sinus formation, as there may be fewer visible signs to suggest actinomycosis. Actinomycosis typically lacks specific radiologic findings and presents with indolent and non specific symptoms. The present is a case of a 35- year-old female with no associated co-morbidities. Over 1.5 years, she developed a progressively enlarging swelling over her left lateral malleolus, accompanied by pain exacerbated by walking. The absence of classic inflammatory signs, draining sinus tracts, or localised tenderness negates the suspicion of an infective etiology. Radiological investigations revealed a soft-tissue tumour, prompting an excisional biopsy. Histopathological analysis confirmed the diagnosis of actinomycosis, highlighting the importance of recognising rare entities with unusual clinical presentations. The present case underscores the diagnostic challenge posed by atypical presentations of actinomycosis and emphasises the necessity of maintaining a broad differential diagnosis to ensure timely recognition and appropriate management of this elusive condition.