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Radiol Case Rep
Radiol Case Rep
Radiology Case Reports
1930-0433
Elsevier

S1930-0433(24)00798-2
10.1016/j.radcr.2024.08.014
Case Report
Madura foot: How MRI aids in diagnosis
Hamdaoui Amina oumayma.hamdaoui@usmba.ac.ma
⁎
Benchekroun Assia
Maasaoui Kaoutar
Elbtioui Hicham
Akammar Amal
El Bouardi Nizar
Haloua Mariam
Lamrani Moulay Youssef
Boubbou Mariam
Maaroufi Mustapha
Alami Badr
Radiology Department, Chu Hassan II Fes, Fes, Morocco
⁎ Corresponding author. oumayma.hamdaoui@usmba.ac.ma
04 9 2024
11 2024
04 9 2024
19 11 55275530
1 7 2024
2 8 2024
4 8 2024
© 2024 The Authors. Published by Elsevier Inc. on behalf of University of Washington.
2024

https://creativecommons.org/licenses/by-nc-nd/4.0/ This is an open access article under the CC BY-NC-ND license (http://creativecommons.org/licenses/by-nc-nd/4.0/).
A 46-year-old farmer living in a rural area, who sustained an injury to his left foot 10 years ago, consulted due to progressive swelling of the same foot. An MRI revealed the “dot-in-circle” sign, suggestive of mycetoma of the foot, also known as Madura foot. This condition primarily affects soft tissues and bones and can occasionally lead to potentially severe visceral complications. Foot involvement is predominant, observed in 80% of cases.

Keywords

Madura food
IRM
Dot-in circle sign
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pmcIntroduction

Madura foot, or maduromycose is a chronic infection caused by fungal or bacterial pathogens that lead to granular lesions, primarily affecting tropical and subtropical regions with a notable predilection for the foot. The condition is classified into eumycetomas, caused by fungi, and actinomycetomas, caused by aerobic bacteria, each requiring different treatment approaches [1]. Diagnosis is typically confirmed through biopsy and microbiological examination, though these methods can sometimes delay treatment. MRI scans are crucial for early detection, particularly for revealing the “dot-in-circle” sign, while CT scans are superior to conventional X-rays in assessing bone changes. Treatment varies: actinomycetomas are treated with a combination of antibiotics, while eumycetomas often respond to imidazole therapies, with surgery as a potential option if medical treatments fail. This report presents a case of a man with a progressively swollen foot, diagnosed with Madura foot via MRI. We discuss the clinical and radiological findings, differential diagnosis, and relevant literature.

Case report

A 46-year-old farmer from a rural area presented with progressive swelling of the left foot. Clinical examination revealed the patient was afebrile and stable, with nonpainful swelling from the left big toe to the forefoot, characterized by multiple fistulous openings draining foul-smelling serous fluid (Fig. 1). X-rays showed no bone erosion, and lab tests were normal, including a white blood cell count of 6900 and a CRP level of 1 (Fig. 2). Mycological and bacteriological samples did not reveal spores, yeast, or mycelial filaments. MRI indicated extensive infiltration of the soft tissues on the dorsal and plantar aspects of the midfoot and forefoot, with increased signal intensity on T2-weighted images and decreased signal on T1-weighted images. The infiltrated area contained well-defined ovoid lesions with the “dot-in-circle” sign on DP FATSAT sequences. Contrast administration revealed marked enhancement of these lesions. Similar infiltrative changes involved the first and second phalanges of the big toe and the head of the third metatarsal bone (Fig. 3). A biopsy confirmed maduromycose, and due to bone involvement, radical surgical intervention, including amputation, was performed.Fig. 1 Shows a swelling extending from the left big toe towards the forefoot, associated with multiple fistulous tracts (black arrow).

Fig 1

Fig. 2 Foot radiography, anterior and lateral views, shows infiltration of the soft tissues of the big toe and forefoot, with no clear visualization of a bone lesion (orange arrow).

Fig 2:

Fig. 3 Axial DP (A), coronal DP (B), sagittal T1 (C), and axial T1 after Gado injection: show diffuse infiltration of the soft tissues on the dorsal and plantar aspects of the midfoot and forefoot, containing ovoid lesions. Some of these lesions are hyperintense on DP FATSAT, surrounded by a hypointense rim, and centered by a hypointense dot, displaying the “dot-in-circle” sign (orange arrows).

Fig 3:

Discussion

Maduromycose, also known as Madura foot, is a chronic granulomatous disease that predominantly affects subcutaneous tissues and can extend to the bone, presenting a significant health threat. This disease mainly affects individuals in rural settings, particularly farmers, who are at risk due to the subcutaneous entry of thorns, splinters, or contaminated tools carrying soil- or plant-dwelling organisms. While the foot remains the most common site of infection, with the hand being the second most frequent site, extrapodal locations such as the abdomen, thigh, neck, buttocks, and nape, though less common, are reported and can lead to potentially fatal visceral lesions [[1], [2], [3]].

The disease is characterized by a triad of symptoms [1]: swelling, abscess formation with fistulas, and the discharge of colored grains, which can be fungal (eumycetoma) or bacterial (actinomycetoma) in origin. Radiographic findings in maduromycose can range from normal to signs of soft tissue enlargement, bone sclerosis, and bone cavities. Comparatively, eumycetoma lesions often present with larger bone cavities (≥1 cm in diameter), while actinomycetoma lesions typically exhibit smaller, more numerous cavities, creating a “moth-eaten” appearance [4]. Advanced imaging techniques, particularly CT and MRI, are crucial for early detection and differentiation from other conditions [5,6]. The “dot-in-circle” sign on MRI, identified as multiple small hypointense foci within hyperintense spherical lesions, is pathognomonic for maduromycose and can also be observed on ultrasound [7,8].

Differentiation from conditions such as osteomyelitis and tuberculosis are essential due to their overlapping symptoms. Biopsy and microbiological culture are indispensable for confirming a definitive diagnosis, with the analysis of filamentous grain characteristics—black for fungal and red for bacterial—playing a pivotal role in guiding treatment decisions [9]. Treatment strategies vary based on the pathogen and the stage of the disease. Antibiotics and antifungals are typically used, though bone invasion often necessitates surgical intervention, including amputation, to prevent further spread and ensure effective management [10].

Conclusion

Madura foot is a chronic infection that primarily affects deep subcutaneous soft tissues in the foot. Diagnosis is typically straightforward in endemic regions and is confirmed through biopsy results, often supported by imaging techniques like MRI, where the “dot-in-circle” sign is considered pathognomonic. The prognosis of the condition is significantly influenced by the extent of bone involvement.

Patient consent

I, the author of the article: “Madura foot: How MRI aids in diagnosis”, approve that the patient gives his consent for information be to published in radiology case reports.

Competing Interests: The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper.
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