Melorheostosis of upper limb: A report of four rare cases

Abstract

Melorheostosis is a rare chronic bone disease, etiology of which remains unclear. It mostly affects lower limbs and clinical features vary in each case. Radiographs show characteristic "candle wax pattern" of hyperostosis. Herein we report four cases of upper limb affection with their symptoms, radiographic findings and treatment. First case presented with gradually progressive swelling in forearm which was initially misdiagnosed as filariasis. Plain radiograph eventually demonstrated melorheostosis of ulna. Second patient had deformity of index finger and pain in hand which was diagnosed on radiograph of hand. Third case presented with progressive flexion deformity of ring and little finger. Fourth patient had ulnar involvement which was an incidental diagnosis. First three patients were managed with bisphosphonates following which there was significant improvement in pain and fourth case was kept on follow-up as he was asymptomatic.

1. Introduction

Melorheostosis or candle bone disease was first described in 1922 by Leri and Jonny. It is a rare, benign, sporadic sclerosing mesodermal dysplasia affecting bones and adjacent soft tissues. Its incidence is 0.9 in 1 million people with equal predilection for both sexes.² The symptoms of melorheostosis include pain, joint contractures and deformities and limb length discrepancy. Radiographic appearance is characteristic and resembles molten wax flowing on sides of candle.¹ Melorheostosis can present in three forms, monostotic, polyostotic or monomelic.^3,4 Long bones of lower extremity are affected more often than upper extremity. The involvement of small bones of the hand (carpals, metacarpals) is uncommon and only few cases have been reported in the literature. Herein we report four interesting cases of melorheostosis affecting upper extremity.

1.1. Case report

Case 1 is a 40-year-old man who presented with progressive painless diffuse non-pitting swelling of left forearm that was gradually enlarging for several weeks. Physical examination revealed a non-pitting subcutaneous swelling of forearm. Previously this swelling was diagnosed by outside physicians as Filariasis. Patient was prescribed antifilarial and antihelminthic medication for several weeks without any improvement, before referring to us. A plain radiograph of forearm was performed which showed endosteal sclerosis of underlying bone ulna in a characteristic “candle wax pattern” with enlarged soft tissue (Fig. 1). The patient was advised bisphosphonate (Alandronate) once weekly with compressive stockings. There was some improvement in swelling at 3-year follow-up.

Fig. 1.

Plain radiograph forearm showed sclerosis of underlying ulna bone in a characteristic “candle wax pattern”.

Case2- A 35-year-old woman presented with pain in right hand and deformity in index finger for 5 months. Pain started from index finger and later involved palm also. Pain was dull-aching and continuous in nature and only occasionally it was so severe that she had to take oral analgesics. She had difficulty in activities like washing clothes and kneading dough. On physical examination, the finger was tender on palpation and there was slight ulnar deviation of index finger at proximal interphalangeal joint. A plain radiograph of hand showed sclerosis of proximal phalanx of index and middle finger, middle phalanx of middle finger, second and third metacarpal, lunate and capitate bones in a characteristic “candle wax pattern” (Fig. 2). The patient was given a single infusion of 4 mg Zoledronic acid. Patient reported significant improvement in pain after the injection.

Fig. 2.

Plain radiograph of hand showed sclerosis of underlying bones.

Case 3- A 40- year-old man presented with complaints of gradually progressive flexion deformity of ring and little fingers of left hand for 5 years. There was no history of pain. On examination, the overlying skin was stiff and there was flexion deformity of ring and index fingers at metacarpophalangeal joint (Fig. 3). Plain radiograph of hand showed sclerosis of middle and proximal phalanx of ring finger, fourth metacarpal and distal ulna in a "candle wax pattern" (Fig. 4). Skeletal survey was done, which showed similar sclerosis in middle third of ulna as well. This patient was also advised for surgical correction of hand deformity but he refused to undergo surgical procedure due to involvement of non-dominant hand. Finally, the patient was advised for hand stretching exercise and is doing well.

Fig. 3.

Clinical photograph of third case showing deformity of index finger.

Fig. 4.

Plain radiograph of hand of third case showed sclerosis of underlying bones in a “candle wax pattern”.

Case 4- A 35-year-old man presented with wrist trauma and incidentally found to have melorheostosis of ulna. Patient was asymptomatic, hence not started on any bisphosphonates. He was kept on follow-up.

2. Discussion

Melorheostosis is a mesodermal dysplasia affecting both bones and adjacent soft tissues. Melorheostosis is most often non-hereditary, and its etiology remains elusive. It follows the innervation of spinal sensory nerves, affecting tissues which correlate with sclerotome and myotomes.⁵ It mostly affects long bones of lower extremity. More than 400 cases have been reported in the literature, of which only few have involved hand bones.⁶ All the three cases we have reported are of upper extremity and out of which small bones of hand are involved in two cases. Melorheostosis is classically a monomelic condition, and this finding was typical in our cases. The disease can cross the joint line and involve other bone in sclerotomal distribution as was in case 3 where ulnar and carpal bones were involved.

Soft tissues overlying affected bones can be stiff, especially in hand as was present in our cases (Case 2 and Case 3). Majority of patients reported so far presented with chronic pain of varying severity and limited range of motion. The pain in melorheostosis can be of somatic, skeletal and neuropathic type; the skeletal type pain is due to abnormal bone formation and causes focal pain over bony lesions as was seen in case 2.

There could be deformity of the hand due to joint contractures which can hamper patients’ routine daily activities due to restricted range of motion, as present in case 2 and case 3. Most reported cases involving the upper extremity are focused on the hand, where, Azuma et al.⁷ and Kawabata et al.⁸ reported two cases each. Other symptoms such as stiffness, swelling, numbness, tingling, carpal tunnel syndrome have also been reported.^{8, 9, 10, 11} Freyschmidt¹² indicated that the symptoms become more severe with increasing degree of hyperostosis and number of bones involved. Two of our patients presented with deformities in hand, one of which also had pain. One patient presented with swelling in forearm region, which was misdiagnosed earlier as filariasis. For diagnosis of melorheostosis, five radiographic patterns have been identified which include osteoma-like pattern, classic candle wax appearance, myositis ossificans-like pattern, osteopathia striata-like, and overlap pattern. The classic radiographic feature of melorheostosis is asymmetrical bands of eccentric dense sclerosis in an irregular, linear pattern of both the endosteal (case 1) and periosteal surfaces (cases 2 and 3) of the cortex often described as molten-wax dripping down from side of a candle.

Clinically, the Melarheostosis should be suspected in patients with concomitant chronic extremity pain, deformities, restricted joint motion, limb swelling, soft tissue masses, and other skin findings. The classic "dripping candle-wax" appearance on radiographs is characteristic finding in these cases.

Management of melorheostosis usually requires multidisciplinary care involving orthopedic surgeon, plastic surgeon, physiotherapist and occupational therapist. The treatment is mainly symptomatic and should be individualized depending on the patient's age, symptoms and location. Melorheostosis can be treated with conservative or surgical methods. Non-surgical method of treatment includes use of oral analgesics, bisphosphonates and Nifedipine.^13,14 Bisphosphonate such as oral pamidronate and intravenous zoledronic acid inhibit bone resorption and show dramatic improvement in pain and size of the melorheostotic lesion in few reports. We have also given bisphosphonates in all three patients and noticed frequent relief in pain and other symptoms. Surgical treatment like surgical debulking or decompression of the mass effect, osteotomies, tendon lengthening, limb lengthening and similar procedures can be performed for cosmetic purpose and in severe and complicated cases.^15,16 In conclusion, the melorheostosis is a rare bone dysplasia. The surgeon should be aware of underlying bone disease in cases of subcutancous edema and deformities of hand. The treatment of the melorheostosis should be individualized.

Appendix A. Supplementary data

The following is the Supplementary data to this article: