Calcific tendonitis of the flexor pollicis longus tendon at the thumb interphalangeal joint in childhood

Abstract

In rare instances, calcific tendonitis may manifest in the pediatric population as inflammatory calcium hydroxyapatite deposition. To our knowledge, there have been no previous case reports involving the flexor pollicis longus tendon at the thumb interphalangeal joint. We present a 9-year-old boy with a painful mass at the right thumb interphalangeal joint. Initial radiographs revealed a 7-mm ovoid calcific mass along the volar soft tissues of the thumb interphalangeal joint. Subsequent ultrasound and magnetic resonance findings further confirmed calcification with surrounding edema. Because the pain was limiting the patient's school activities, his family elected for excisional biopsy of the calcific mass. Pathology ultimately revealed prominent dystrophic calcifications with surrounding granulomatous inflammation, consistent with calcific tendonitis.

Keywords: Calcific tendonitis; flexor pollicis tendon; magnetic resonance imaging; pediatric; radiograph; ultrasound.

Figure 1.

Lateral radiograph of the right thumb showing an ovoid calcific density (arrow) longitudinally oriented and superficial to the volar aspect of the interphalangeal joint.

Figure 2.

Ultrasound of the calcific mass. (a) Longitudinal view demonstrating that the ovoid hyperechoic mass (between calipers) is superficial to the longitudinal fibers of the tendon (T). (b) Transverse image showing no color Doppler flow in the hyperechoic mass, although there is increased pericalcific flow reflecting inflammation.

Figure 3.

MRI of the right thumb. (a) Axial T2 fat-saturated image demonstrating the calcified mass lesion (arrow) markedly hypointense, consistent with calcification, with surrounding hyperintense edema. (b) Sagittal T1 fat-saturated postcontrast image showing the mass lesion (arrow) superficial to the tendon (T) with surrounding enhancement from edema and inflammation.