Imaging features of periosteal chondroma manifesting as a subcutaneous mass in the index finger

Abstract

Periosteal chondroma is a rare benign hyaline cartilage neoplasm that occurs most commonly in the metaphases of long tubular bones. We present a unique case of periosteal chondroma arising in the proximal phalanx of the left index finger in a 12-year-old boy. Physical examination revealed a slightly protuberant, subcutaneous mass. Plain radiographs and computed tomography scans showed a periosteal lesion producing saucerization of the cortex and subjacent cortical sclerosis, without internal matrix calcification. On magnetic resonance imaging, the lesion exhibited intermediate signal intensity on T1-weighted images and high signal intensity on T2-weighted images. Contrast-enhanced fat-suppressed T1-weighted images demonstrated peripheral and septal enhancement. The patient underwent a marginal excision with curettage of the underlying bone cortex. Histological examination confirmed the diagnosis of periosteal chondroma. There has been no evidence of local recurrence eight months after surgery. Periosteal chondroma can protrude into the subcutaneous soft tissue causing a palpable mass. Recognition of the typical radiological features can lead to an accurate diagnosis of this rare condition.

Figure 1

Photograph shows a slightly protuberant, subcutaneous mass in the radial aspect of the proximal phalanx of the left index finger.

Figure 2

Anteroposterior radiograph reveals saucerization of the underlying cortex and a rim of sclerosis on the radial surface of the proximal phalanx.

Figure 3

Coronal (a) and axial (b) computed tomography scans show cortical overhanging margins at the periphery of the lesion (arrows).

Figure 4

Axial magnetic resonance imaging showing a well-defined juxtacortical mass with intermediate signal intensity on T1-weighted image (a) and high signal intensity on T2-weighted image (b). Contrast-enhanced fat-suppressed T1-weighted image (c) demonstrates peripheral and septal enhancement.

Figure 5

Histological finding of periosteal chondroma. The tumor is composed of bland chondrocytes in an abundant hyaline cartilage matrix.