A 14-year-old boy was referred by his primary care pediatrician for evaluation of a 6-month history of painful unilateral clubbing of the right great toe (Figure 1A), with no other associated alterations. There was no history of trauma. On plain x-rays of the right foot, an area of increased density was identified on the lateral aspect of the phalanx of the right great toe, compatible with bone exostosis (Figure 1B). Histologic examination revealed a disc of disorganized cartilaginous tissue beneath a fibrous periostium, with ossification at its base that was continuous with the bone trabeculae (Figure 1C); these findings were consistent with subungual osteochondroma. The absence of exostoses on the distal femur or proximal tibia and the absence of similar lesions in family members helped to exclude hereditary multiple exostoses. The patient was followed up at 9 months and no recurrence of the lesion was observed.

Figure 1

(0.28MB).

Subungual osteochondroma is a rare benign tumor that usually affects young adolescents and is more common in males. The growth of endochondral bone is asymptomatic during childhood, but can become evident during adolescence. There is usually no history of trauma. Subungual osteochondroma is differentiated histologically from exostosis by the presence of hyaline cartilage, and morphologically exostoses are typically flat or dome-shaped on plain x-rays, while osteochondromas are sessile, pedunculated, and clearly circumscribed.