Osteochondroma is a cartilaginous benign neoplasms, usually located at the metaphyseal region of the long bones, especially at the proximal phalanx.1 Solitary form is rare in the hand, but when it occurs, it usually is associated with hereditary multiple osteochondromatosis.1-3 The incidence of solitary form in the absence of hereditary multiple osteochondromatosis is not known. This article presents a case of a solitary form of phalangeal ostechondroma causing extensor tendon attrition in a 2-year-old child.
A 24-month-old patient presented with a 6-month history of painless enlargement on the dorsum of the metacarpophalangeal joint of the right long finger. Examination revealed a palpable, well-defined area of bony prominence on the dorsum of the proximal phalanx adjacent to metacarpophalangeal joint of the long finger (Figure 1). The patient had limited finger flexion at the metacarpophalangeal joint of the long finger with full range of motion on the remaining digits.
Physical examination revealed no other abnormalities or bony growths. Radiographs of the hand showed a well-marginated, uniformly dense, bony mass arising from the metaphyseal region of the dorsal cortex of the proximal phalanx (Figure 2). Radiographic examination of the contralateral hand showed no bony abnormalities. Due to the history of rapid growth and functional deficit, an excisional biopsy was performed with a straight 3- to 4-cm dorsoradial incision over the metacarpophalangeal joint. Extensor apparatus was elongated due to gradual outgrowth of the mass.
Intraoperatively, a thickened cartilaginous cap was removed (Figure 3 and 4). A segment of periosteum and cortical bone was excised along with the cartilaginous lesion. Histopathological examination showed multiple loculated cartilaginous tissue with limited bony spicules and no atypia, which are all consistent with ostechondroma (Figure 5). Twelve months postoperatively, the patient reported complete resolution of all symptoms without any recurrence.
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Figure 1: Clinical presentation prior to surgery. Figure 2: The patient was not able to make a composite fist. Oblique radiograph of the hand shows sclerotic bony prominence on the dorsal aspect of the proximal phalanx. Figure 3: Intraoperatively, a rectangular shaped osteotomy was made to elevate the cartilaginous cap. Figure 4: Removal of the osseous cartilaginous tissue.
Osteochondromas are rare lesions in the hand and are commonly confused with proliferative periosteal processes such as turret exostosis or florid reactive periostitis, which are collectively commonly known as bizarre parosteal osteochondromatous proliferations or Noras lesions.4 The most common clinical presentation for solitary osteochondroma is a painless swelling on the dorsum of the digit along with an angular deformity.3 It may also be presented as a cause of childhood trigger finger,5 swan-neck deformity,6 blocked interphalangeal joints,2 and necrosis of the overlying skin.7 The lesion is believed to be congenital in origin and it has been reported as early as 4 years. Other osteochondromatous proliferations in phalanges, including bizarre parosteal osteochondromatous proliferations, are commonly seen in adulthood during the third and fourth decade.8 Solitary osteochondroma and bizarre parosteal osteochondromatous proliferations both present as a mushroom like outgrowth at the metaphyseal region of the bone with well-defined margins and intense calcification. Solitary osteochondroma is commonly located at the proximal phalanx, whereas bizarre parosteal osteochondromatous proliferations are usually located at the middle and distal phalanges.
Both lesions do not show any periosteal reaction on the radiograph. In osteochondroma, the lesion and the bone have a uniform density with well-marginated outgrowth and a broad base with no disruption in the cortex. Bizarre parosteal osteochondromatous proliferation, however, shows irregular calcific outgrowths with a narrow base. Often there is no continuity between the cortex of the host bone and the lesion.
Histopathology of solitary osteochondroma shows three distinct types of tissue: cartilage, bone, and fibrous tissue. Histologic transition between the 3 regions is always well defined and smooth in osteochondroma and bizarre parosteal osteochondromatous proliferation. Grossly, the presence of a cartilage cap is typical for both lesions. In osteochondroma, endochondral ossification at the deeper parts of the lesion is well organized whereas in bizarre parosteal osteochondromatous proliferation, irregular calcified cartilage matrix is stained blue on hematoxylin-eosin satin. Immediately under the capsule, there is an abundant fatty or hemopoietic marrow stroma in osteochondroma. This is replaced by loose fibrous stroma with spindle cells in bizarre parosteal osteochondromatous proliferation. Both lesions do not display any atypia as seen in osteosarcoma.
Figure 5: Histopathology of the lesion at X40 magnification shows a well-organized cancellous bone
- Huvos AG. Bone Tumors: Diagnosis, Treatment and Prognosis. 2nd ed. Philadelphia, Pa: WB Saunders; 1991.
- Karr MA, Aulicino PL, DuPuy TE, Gwathney FW. Osteochondromas of the hand in hereditary multiple exostosis: report of a case presenting as a blocked proximal interpahalangeal joint. J Hand Surg [Am]. 1984; 9:264-268.
- Moore JR, Curtis RM, Wilgis EF. Osteocartilaginous lesions of the digits in children: an experience with 10 cases. J Hand Surg [Am]. 1983; 8:309-315.
- Yuen M, Friedman L, Orr W, Cockshott WP. Proliferative periosteal processes of phalanges: a unitary hypothesis. Skeletal Radiol. 1992; 21:301-303.
- Al-Harthy A, Rayan GM. Phalangeal osteochondroma: a cause of childhood trigger finger. Br J Plast Surg. 2003; 56:161-163.
- Stern PJ, Phillips D. Phalangeal osteochondroma: an unusual cause of swan-neck deformity. J Hand Surg [Am]. 1986; 11:70-73.
- Ganzhorn RW, Bahri G, Horowitz M. Osteochondroma of the distal phalanx. J Hand Surg [Am]. 1981; 6:625-626.
- Michelsen H, Abramovici L, Steiner G, Posner MA. Bizarre parosteal osteochondromatous proliferation (Noras lesion) in the hand. J Hand Surg [Am]. 2004; 29:520-525.
Drs Ozer and Peterson are from the Department of Orthopedics, Denver Health Medical Center, and the University of Colorado, School of Medicine, Denver, Colo.
Reprint requests: Kagan Ozer, MD, Denver Health Medical Center, 777 Bannock St, MC 0188, Denver, CO 80246.