Eumycetoma Osteomyelitis of the Calcaneus in a Child: A Radiologic-Pathologic Correlation following Total Calcanectomy

Abstract

Fungi are unusual causes of pedal osteomyelitis in children and adolescents. Eumycetoma is a chronic cutaneous and subcutaneous infection caused by various genera of fungi. A provisional diagnosis of foot mycetoma is made after clinical assessment. Radiologic-pathologic correlation is an essential supplement for the accurate diagnosis of osteoarticular infections. This paper aims to sensitize orthopedic surgeons, radiologists, and pathologists to the importance of correlative imaging findings in relation to surgical and microscopic pathology in osteoarticular infections, specifically eumycetoma osteomyelitis of the foot. From our review of the published data, the present case is the first report of radiologic-pathologic correlation in eumycetoma osteomyelitis of the calcaneus. This paper describes a case of eumycetoma osteomyelitis of the calcaneus in a child in which diagnostic X-rays and magnetic resonance imaging (MRI) were correlated with the surgical and microscopic pathologic features, for establishing an appropriate diagnosis and treatment. We conclude that there is a significant agreement between radiologic and pathologic evaluation for assessment of eumycetoma osteomyelitis of the calcaneus. Radiologic-pathologic correlation amplified our interpretation of imaging information available on plain radiographs and MRI and augmented diagnostic confidence. Similarly, anatomic-histopathological correlations consolidated diagnostic accuracy.

Figure 1

(a) T1-weighted sagittal MRI of the right foot. Note the altered marrow signals seen almost totally replacing the marrow texture of the calcaneus and to a lesser extent the opposing posteromedial aspect of the talus (black arrow) eliciting an abnormal low signal. (b) T2-weighted sagittal MRI of the right foot. Note the abnormal high signals replacing the marrow texture of the calcaneus. Note the multiple low-intensity lesions (black arrows) that may represent a conglomerate of grains in the background of diffuse high-intensity inflammatory bone changes. These low-intensity lesions are known as dot in circle. (c) T2-weighted sagittal MRI of the right foot. Note the low-intensity cavitary lesion of the posterior calcaneus (white arrow) that was found to correlate well to a conglomerate of black grains noticed in the gross pathologic specimen of the calcaneus. Note the same low-intensity lesion (black arrow) in the background of diffuse hyperintense inflammatory soft tissue changes (dot in circle). (d) T2-weighted coronal MRI of the right foot. Note the multiple small low-intensity lesions (black arrows) that may represent a conglomerate of grains in the background of diffuse hyperintense inflammatory bone changes. The same lesion is depicted in the soft tissue (white arrow).

Figure 2

(a) Intraoperative images of calcaneus employing the heel splitting approach. Note the conglomerate of black grains arising from the cavity on the medial surface of calcaneus (white arrow). (b) Intraoperative images of calcaneus employing the heel splitting approach. Note the large medial cavity (white arrow) and cortical erosion covered by minute black grains (black arrow).

Figure 3

(a) Intraoperative images of superior surface of calcaneus employing the heel splitting approach. Note the extensive conglomerates of black grains scattered over that surface (solid arrows). Note the complete destruction of the articular cartilage of the posterior facet of the subtalar joint (hollow arrows). (b) Operative images of superior surface of calcaneus following total resection, employing the heel splitting approach. Note the extensive conglomerates of black grains scattered over that surface (white solid arrows) and the articular cartilage erosions of the anterior and middle facets of the subtalar joint (hollow white arrows). Complete destruction of the articular cartilage of the posterior facet of the subtalar joint with gross deformation is depicted (hollow black arrow). (c) Operative images of inferior surface of the calcaneus following total resection, employing the heel splitting approach. Note the presence of multiple bony cavities of various sizes (white arrows). Foci of black granular discharge are depicted (hollow arrows). (d) Brown fungal colonies with surrounding inflammatory cells and fibrosis (H and E, ×400).