Actinomycetoma of the Elbow Following Road Traffic Injury: Importance of Early Recognition and Management

INTRODUCTION

Mycetoma is a chronic, progressively destructive infection of the skin and subcutaneous tissues that remains an important yet neglected tropical disease. It is characterised by tumefaction, draining sinuses, and granular discharge, and may extend to involve deeper structures if not diagnosed early.^[1,2]

Depending on the causative organism, mycetoma is classified into actinomycetoma, caused by filamentous bacteria, and eumycetoma, caused by true fungi.^[1,3] These two entities differ in their epidemiological distribution, clinical course, and response to therapy. In India, actinomycetoma is reported more frequently from southern regions and parts of Rajasthan, whereas eumycetoma predominates in arid and desert areas of northern India.^[2,4]

The disease predominantly affects young to middle-aged males, particularly those engaged in outdoor or manual occupations, and is often associated with a history of trivial or unrecognised trauma that facilitates inoculation of the organism into subcutaneous tissue.^[4,5] Delayed presentation is common due to the painless and slowly progressive nature of the disease, leading to significant morbidity and functional impairment. Early recognition and appropriate medical management are therefore essential to prevent complications and avoid surgical interventions.

The disease typically follows traumatic inoculation of causative organisms into the skin and subcutaneous tissue, leading to chronic granulomatous inflammation and formation of sinus tracts with granular discharge.

Actinomycetoma develops following the traumatic implantation of filamentous bacteria into the skin and subcutaneous tissues, often through minor cuts or abrasions. Once inoculated, the organisms proliferate locally and aggregate to form compact microcolonies known as grains. These grains elicit a chronic inflammatory response characterised by granuloma formation, suppuration, and fibrosis.

Progressive extension of the infection leads to the formation of nodules and interconnected sinus tracts that discharge purulent material containing grains. Over time, the disease spreads contiguously through surrounding soft tissues and may involve deeper structures, including fascia, muscle, and bone, resulting in deformity and functional limitation if left untreated.

CASE REPORT

A 29-year-old male, a juicer by occupation, presented with multiple discharging lesions over the right elbow. He gave a history of a road traffic injury 2 years prior to presentation, during which he sustained a penetrating injury to the right elbow with possible contamination from road dust and soil. This likely acted as a portal of entry for the organism into the subcutaneous tissue. Approximately three months after the injury, he noticed a swelling over the affected area, which gradually increased in size and number over the subsequent 2 years.

The patient reported intermittent greenish seropurulent discharge from the lesions, which was insidious in onset, non-foul-smelling, and associated with itching. The discharge and crusting progressively worsened over time. There was no associated pain or restriction of movement of the right elbow joint. He denied any history of fever, weight loss, or systemic symptoms.

Cutaneous examination revealed a hyperpigmented, indurated plaque with multiple discharging sinuses over the extensor aspect of the right elbow. The surrounding skin was hyperpigmented and indurated, forming a raised plaque. Seropurulent discharge was noted from the sinus openings [Figure 1]. There was no local warmth or tenderness, and the range of movement of the elbow joint was preserved.

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Figure 1: Multiple seropurulent-discharging sinuses with surrounding induration and hyperpigmentation demonstrating classical sinus-tract formation.

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Gram staining of the discharge revealed a few gram-positive cocci arranged in pairs and clusters. Histopathological examination demonstrated a chronic non-necrotising granulomatous inflammatory response with foreign body giant cells. Basophilic filamentous bacterial colonies surrounded by Splendore-Hoeppli material were observed at focal areas. The colonies were well visualised in the central field of the section and highlighted at appropriate magnification. Periodic acid-schiff staining showed positive actinomycotic colonies, supporting a diagnosis of actinomycetoma [Figure 2]. Culture and sensitivity testing yielded growth of Staphylococcus aureus and Enterococcus faecalis. Culture for actinomycetes was attempted; however, no growth was obtained, which may be attributed to the fastidious nature of the organism and prior antibiotic exposure. A key diagnostic consideration in this case was botryomycosis, particularly due to the isolation of Staphylococcus aureus on culture. However, several findings strongly favoured a diagnosis of actinomycetoma. Histopathological examination demonstrated basophilic filamentous bacterial colonies surrounded by Splendore-Hoeppli material along with a chronic granulomatous inflammatory response, which are characteristic of actinomycetoma.^[1,6]

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Figure 2: Microscopic view showing Splendore-Hoeppli phenomenon (green arrow) (Haematoxylin and eosin stain, x400).

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Although Gram staining predominantly showed gram-positive cocci, the presence of occasional gram-positive bacilli and the known limitations of Gram stain in consistently demonstrating filamentous forms in chronic or partially treated lesions must be considered. Furthermore, cultures from chronic discharging sinuses frequently yield secondary colonising organisms such as Staphylococcus aureus, which may not represent the primary etiological agent.^[5]

The absence of fungal elements on the potassium hydroxide mount and fungal culture effectively ruled out eumycetoma. Taken together, the clinicopathological correlation, particularly the characteristic histopathological findings, supported a diagnosis of actinomycetoma over botryomycosis. A deep biopsy was obtained from the affected area to confirm the diagnosis. Radiological evaluation revealed soft tissue thickening around the elbow joint without definitive evidence of bony involvement [Figure 3], suggesting early disease and contributing to the favourable response to medical therapy.

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Figure 3: X-ray right elbow joint lateral view showing no obvious osseous involvement of actinomycetoma. Early stages of the disease may not demonstrate radiographic lytic changes.

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The patient had previously received intravenous crystalline penicillin and benzathine penicillin at a local hospital, with no significant clinical improvement. After confirmation of the diagnosis, the patient was initiated on a modified Welsh regimen with the objective of achieving clinical remission and preventing progression to deeper tissue or bony involvement. The treatment plan consisted of intravenous amikacin administered at a dose of 15 mg/kg/ day in divided doses, along with oral trimethoprim-sulfamethoxazole and rifampicin at standard weight-based dosages. The regimen was planned for one to three cycles, each of 21 days’ duration, with a 15-day drug-free interval between cycles.

The antibiotic regimen used also provided adequate coverage against the isolated organisms, including Staphylococcus aureus, thereby addressing the possibility of secondary bacterial infection. The expected outcome of therapy was resolution of active sinuses, cessation of discharge, and prevention of further tissue destruction. The patient demonstrated a favourable clinical response, with a gradual reduction in seropurulent discharge, healing of sinus tracts, and resolution of active lesions following treatment. At follow-up, the elbow showed healed lesions with residual scarring and hyperpigmentation, without recurrence or functional impairment [Figure 4].

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Figure 4: Healing sinuses following treatment- crusted, partially healed sinuses with decreased inflammation over the elbow after starting the modified Welsh regimen.

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DISCUSSION

Mycetoma remains a chronic and disabling infectious disease with significant morbidity in endemic regions, particularly in developing countries. Despite being classified as a neglected tropical disease, delayed diagnosis and inadequate treatment continue to contribute to disease progression and long-term disability. Actinomycetoma, the bacterial variant, is known to have a relatively better response to medical therapy compared to eumycetoma, emphasising the importance of early etiological identification and prompt initiation of appropriate treatment.^[1]

Several studies from India have documented marked regional variation in the distribution of mycetoma. Actinomycetoma has been reported more frequently from southern India, southeastern Rajasthan, and parts of central India, whereas eumycetoma predominates in arid and desert regions of northern India.^[2,4] This geographic heterogeneity has been attributed to climatic factors, soil characteristics, occupational exposure, and differences in causative organisms. The present case is consistent with these observations, as the patient originated from southern India and demonstrated clinical and histopathological features suggestive of actinomycetoma.

The disease predominantly affects young adult males engaged in outdoor or manual occupations, which increases the likelihood of traumatic inoculation.^[7] Talwar and Sehgal reported foot involvement in nearly seventy percent of cases; however, involvement of atypical sites such as the upper limb, trunk, or elbow has also been documented.^[3,4] The present case highlights elbow involvement following a road traffic injury, underscoring the need to consider mycetoma in the differential diagnosis of chronic nodular or sinus-forming lesions even at uncommon anatomical sites.

A history of trauma is a well-established predisposing factor in the pathogenesis of mycetoma. Minor or unrecognised trauma facilitates inoculation of the organism into subcutaneous tissues, initiating a slowly progressive infection.^[4,5] In the current case, lesion onset following a road traffic injury strongly supports traumatic implantation as the initiating event. However, the painless and indolent nature of the disease often leads to delayed presentation, as observed in this patient.

Diagnosis of actinomycetoma relies on a combination of clinical features, microbiological examination, histopathology, and radiological assessment when deeper tissue involvement is suspected. Demonstration of filamentous bacterial colonies with surrounding Splendore-Hoeppli phenomenon on histopathology, along with supportive Gram staining and culture findings, remains central to diagnosis.^[1,6] These diagnostic modalities have been emphasised in previous Indian and international studies and remain especially valuable in resource-limited settings.

Medical management is the mainstay of treatment for actinomycetoma. Several antibiotic regimens have shown favourable outcomes, particularly combination therapies incorporating aminoglycosides and sulphonamides.^[5,8] The modified Welsh regimen has been widely used in India with satisfactory clinical response and reduced need for surgical intervention. In the present case, treatment with the modified Welsh regimen resulted in marked clinical improvement, with resolution of active sinuses and healing with residual scarring, consistent with outcomes reported in earlier studies.^[5,8]

Delayed diagnosis continues to pose a major challenge in the management of mycetoma. Sawatkar et al. reported an average disease duration exceeding 3 years prior to diagnosis, attributing delays to the asymptomatic nature of early disease, lack of health awareness, and inadequate treatment at the primary care level.^[8,9] The prolonged disease course observed in the present case further reinforces these observations.

Bone involvement is a critical determinant of prognosis and treatment complexity in mycetoma. Advanced disease with osseous involvement often necessitates surgical intervention or amputation, whereas early medical therapy can prevent disease progression.^[10] The absence of bone involvement in this case contributed to a favourable outcome, highlighting the importance of early diagnosis and timely initiation of appropriate antimicrobial therapy.

Overall, this case emphasises the need for heightened clinical suspicion for actinomycetoma in patients presenting with chronic discharging sinuses, particularly in endemic regions and in the presence of antecedent trauma. Early recognition, accurate diagnosis, and appropriate combination antibiotic therapy can significantly improve patient outcomes and reduce long-term morbidity.

CONCLUSION

This case highlights an unusual presentation of actinomycetoma involving the elbow following trauma, an uncommon anatomical site compared to the classical involvement of the foot. It also underscores the diagnostic challenge posed by concomitant bacterial growth on culture, which may lead to confusion with conditions such as botryomycosis. The case emphasises the importance of correlating histopathological findings with clinical features for accurate diagnosis and timely initiation of appropriate therapy.