A 50-year-old farmer presented to us with fever and serosanguineous discharging swelling over the dorsum of right foot. To start with the growth was small, approximately 1-2 cm in size and without any pain and discharge. Over the last 18 months, it has progressed gradually and occupied the whole of the dorsum of right foot. Past history was nothing significant, no history of trauma or injury to the foot, non-diabetic, non-hypertensive and not suffering from tuberculosis. But 3 months back at the local hospital the patient was diagnosed as having tuberculosis and treated with anti-tubercular drugs. However, there was no improvement even after 2 months of treatment, hence discontinued the treatment. Local examination revealed a grossly swollen entire dorsum of the right foot with intense erythema, numerous elevated, well-demarcated small to large nodular lesions with few discharging sinuses. Sinus openings were inflamed and mostly blocked with dried pus. The foot was grossly deformed, and it was tender. Veins of the right leg were dilated and pitting edema extended almost up to the knee. Discharge was yellowish, purulent and foul smelling without any apparent granules [Figure 1]. Pus was collected in a sterile bottle by aspirating with sterile Pasteur pipette. A piece of biopsy 4 x 6 mm was obtained from one of the nodular swellings and subjected for microbiological and histopathological examination.
A thorough physical examination revealed no other abnormality except that the patient had mild fever. His hemoglobin was 10 g/dl, total leucocyte count was 11,900/mm3, polymorphonuclear leucocytes 80%, ESR 40 mm/h [Westergen's method]. HIV seronegative, LFT, RFT and electrolytes were within normal limits. There is no evidence of any other disease or abnormality.
The radiological examination of antero-posterior and lateral view of right foot showed soft tissue density occupying the inter-pharyngeal and metatarsal joint space causing spreading of 2nd and 3rd inter-pharyngeal joint space and there was no bone involvement.
In the laboratory, a smear was prepared from the sample and stained with Gram's stain, which revealed thin, long, branching, Gram-positive filamentous bacilli [Figure 2]. On modified Ziehl-Neilson stain (1% H2SO4 decolorizer) the filaments were weakly acid fast.
Culture was done on sheep blood agar and Sabouraud's dextrose agar (SDA) with antibiotics. A small, dry, granular, wrinkled chalky white to cream colored colonies were grown after a week's incubation at 37oC. The colonies were identified as Nocardia species by culture smear and were subjected for biochemical testing for confirmation and speciation. The colonies were inoculated onto different decomposition media like urease, casein, xanthine, and hypoxanthine to see the hydrolysis of media. These differential plates were incubated at 30oC for 3 weeks. As per the morphological, cultural and biochemical characteristics the isolates was identified as N. asteroides.
The histopathological examination of biopsy revealed structure of skin, sub-cutaneous tissue and sinus tract lined by granulation tissue. Few irregular lobulated light basophilic granules were present. The granules are not bordered at the periphery by the eosinophilic material; the filaments in the granules are weak acid fast giving an impression of multiple discharging sinuses of foot - Actinomycetes Mycetoma - Nocardia species.
The patient showed dramatic improvement with Minocycline, Dapsone, and Amikacin in cycles of 5 weeks followed by an additional course of Ciprofloxacin. After 6 months of treatment, the lesion healed with significant scarring.