gms | German Medical Science

Objectives: Osteochondromas are the most common benign tumors of the skeletal system. Generally, they arise in the metaphyseal region of long tubular bones such as distal femur, proximal tibia or proximal humerus. Hand involvement, however, is rarely observed. In patients with hereditary multiple osteochondromas (HMO), hand involvement mostly comprises the area at the distal end of the metacarpals and the proximal part of the phalanges and is associated with complications including angular deformity, metacarpal shortening, mechanical irritation during joint motion or impingement on the neurovascular bundles. In the current literature, no report exists about osteochondromas in continuity with the medial base of the 5th metacarpal and their surgical treatment.

We present the case of a 22-year-old patient with an unpainful swelling at the palmar base of the 4th and 5th metacarpals of the left hand. Remarkably, the swelling had grown for years without being symptomatic. Lately, it started to impinge on nearby structures and even began limiting the ability to properly clench into a fist.

Methods: Clinical examination, diagnostic radiology, computed tomography as well as magnetic resonance tomography were used to evaluate the tumor.

Results and conclusion: Clinical examination presented a swelling of 4 cm in diameter over the palmar base of the 4th and 5th metacarpals. Adhesion of flexor tendons was assumed due to the inability of fully flexing these fingers. The neurovascular bundles appeared to be unaffected. Computed tomography of the tumor showed an exophytic mass growing from the medial base of the 5th metacarpal (Figure 1B [Fig. 1]). Magnetic resonance tomography demonstrated medullary continuity as well as a cartilage cap characteristic of osteochondroma (Figure 1C [Fig. 1]). A complete surgical excision of the lesion with medial approach was performed under general anaesthesia. Intraoperative examination confirmed that the tumor originated from the medial base of the 5th metacarpal bone. The flexor tendons as well as the neurovascular bundles were carefully dissected from the tumor. The tumor was excised in toto (Figure 1D [Fig. 1]). Histopathological examination confirmed the diagnosis of osteochondroma. Active finger movements and intensive physiotherapy was started 2 weeks after surgery. At the final follow-up examination, an excellent recovery of the fingers was observed 4 weeks postoperatively with full range of motion and no loss of sensitivity.

This case demonstrates an unusual localisation of osteochondroma in the hand of a patient with HMO which has not been reported so far and establishes the possibility of a complete excision by surgical removal via medial approach.