Chronic swelling of the foot

Skeletal Radiology, Apr 2017

Dyan V. Flores

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Chronic swelling of the foot

Skeletal Radiol Chronic swelling of the foot Dyan V. Flores 1 0 2 Amorsolo Street, Legaspi Village, Makati City, Metro Manila 1229 , Philippines 1 Department of Radiology, Makati Medical Center 2 Dyan V. Flores - Discussion In the case demonstrated, radiography of the great toe (Fig. 1) shows sclerosis and periostitis on either side of the proximal phalanx of the first digit, and flowing sclerosis in the medial aspect of the proximal phalanx of the second digit. Axial and coronal T2-weighted fat-suppressed images (Fig. 2) show ovoid, hyperintense lesions with low signal rims and faint, tiny central dots (dot-in-circle sign), particularly in the dorsal and medial aspects of the forefoot. Coronal (Fig. 3) and axial (Fig. 4) T1-weighted and T1-weighted fat-suppressed postcontrast images demonstrate enhancement of these lesions separated by internal, non-enhancing, low-intensity tissues. Histopathology confirms the presence of filamentous colonies of Actinomyces (Fig. 5). Mycetoma, first described in the Madura district of India in 1842 [ 1–3 ], is a clinical entity referring to a chronic, debilitating, granulomatous disease of soft tissues, usually of the foot, resulting from infection either with filamentous bacteria (actinomycetoma) or true fungi (eumycetoma) [ 1, 2, 4–6 ]. It is endemic in equatorial, tropical, and subtropical regions, including the Middle East [ 1, 4, 5 ], but is not well known in the USA and Europe [ 5 ], except in migrant populations [ 7 ]. Data on its prevalence have been few and far between. A meta-analysis by van de Sande et al. in 2013 reviewed several single-center studies from various countries and estimated a prevalence between <0.01 to 3.49 cases per 100,000 The case presentation can be found at doi: 10.1007/s00256-017-2642-5 inhabitants, with Mexico, Sudan, and India being the most commonly affected countries [ 3 ]. Patients are typically male [ 1, 3, 6 ] and under 30 years old [ 3, 6 ]. An update from the Mycetoma Research Center in Sudan released in 2015 predicted higher numbers in the future, with possibly more accurate estimates of its exact global burden as more research and surveillance programs are implemented [6]. The disease is usually slow and painless [ 5 ], with the organism first lodging in the soft tissues typically as an aftermath of skin trauma [ 1, 4–6 ], before multiplying and forming colonies that spread along fascial planes to the deeper soft tissue structures [ 1, 6 ]. It may be confined to the soft tissues for years [ 4–6 ], but has the potential for imminent osseous changes such as periosteal reaction and cortical erosion that almost always commences from the outside, in contrast to the centrifugal spread typical of bacterial osteomyelitis [ 1 ]. The clinical picture of mycetoma is uniform, regardless of the causative species [ 1 ]. The characteristic triad includes a painless subcutaneous mass, draining sinuses, and exuding Bgrains^ representing either a conglomerate of fungal hyphae [ 1, 6, 7 ], or bacteria in microabscesses [ 8 ], although these findings may not be present until the advanced stages, when extensive bone and soft tissue damage has already occurred [ 4 ]. Moreover, constitutional symptoms and signs are rare and may occur only after secondary bacterial infection of open sinuses [ 1 ]. The available diagnostic tests for mycetoma are few and not without limitations; early laboratory diagnosis before the appearance of sinuses and grains is particularly challenging [ 8 ]. Isolation of the fungal grains may be performed either via a deep-seated biopsy or aspiration cytology [ 2 ], necessitating the use of special stains for thorough identification of the causative organism [ 2 ]. Microbiological culture provides definitive diagnosis, but may take several weeks to months [ 2, 6, 9 ], with the potential for inadvertent contamination, and Mycetoma should be part of the differential diagnosis in any case of a chronically swollen foot, particularly one with discharging sinuses. MRI may be important in the early recognition of the disease to prevent progressive bone destruction requiring surgery. The dot-in-circle sign that can be seen both in MRI and ultrasound reflects the unique pathologic features of the disease, is easy to recognize, is virtually pathognomonic of mycetoma, and may suggest the possible diagnosis without the need to wait for the histologic outcome. Compliance with ethical standards Grants received None. Disclosures None. Conflicts of interest None. 1. Fahal A , Hassan M. Mycetoma . Br J Surg . 1992 ; 79 ( 11 ): 1138 - 41 . 2. Van de Sande W , Fahal A , Goodfellow M , Mahgoub E , Welsh O , Zijlstra E . Merits and pitfalls of currently used diagnostic tools in mycetoma . PLoS Negl Trop Dis . 2014 ; 8 ( 7 ): e2918 . 3. Van de Sande W. Global burden of human mycetoma: a systematic review and meta-analysis . PLoS Negl Trop Dis . 2013 ; 7 ( 11 ): e2550 . 4. Bouziane M , Amriss O , (...truncated)


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Dyan V. Flores. Chronic swelling of the foot, Skeletal Radiology, 2017, pp. 1017-1018, Volume 46, Issue 7, DOI: 10.1007/s00256-017-2641-6