Skeletal Radiol (2014) 43:243–246 DOI 10.1007/s00256-013-1720-6

CASE REPORT

Surface chondromyxoid fibroma of the distal ulna: unusual tumor, site, and age Ibrahim Fikry Abdelwahab & Michael J. Klein

Received: 4 June 2013 / Revised: 14 August 2013 / Accepted: 22 August 2013 / Published online: 21 September 2013 # ISS 2013

Abstract Chondromyxoid fibroma (CMF) is a rare benign cartilage congener tumor comprising less than 1 % of primary bone tumors. Although the age range is wide, it is most commonly seen in the second and third decades. The most frequent location of CMF is in the long tubular bones of the lower extremities, particularly the proximal tibia and distal femur. Although the majority of chondromyxoid fibromas present as intramedullary tumors, a subgroup of chondromyxoid fibromas arising as surface lesions of the bone has recently been described. These are associated with an older mean age and an increased incidence of matrix calcifications. Chondromyxoid fibromas are rare in the distal ulna. We report a CMF presenting as a surface lesion of the distal metaphysis of the left ulna in a 41-year-old woman. We reviewed the literature on chondromyxoid fibromas involving the ulna and found that out of 22 cases, 1 was in the distal ulna, 13 in the proximal ulna, and in the remaining 8 the ulnar sites were unspecified. No case of chondromyxoid fibroma in the published literature had been designated as a surface lesion. Our own unpublished data include 70 chondromyxoid fibromas, 4 of which are in the ulna. Two of these are in the distal portion.

Keywords Chondromyxoid fibroma . Surface bone tumors . Benign bone tumors . Ulna

Introduction Chondromyxoid fibroma (CMF) is a rare benign cartilage congener tumor constituting less than 1 % of primary bone tumors. It is well circumscribed, usually eccentric, and most frequently occurs in the tibial metaphysis in the second and third decades. While the vast majority of reported cases are medullary in location, a small number of these tumors have been reported to arise as surface lesions [1]. CMF is characterized histologically by a zonal arrangement of relatively hypocellular myxochondroid matrix arranged in pseudolobular aggregates separated by zones of cellular stroma containing mononuclear cells and osteoclast-like giant cells. The nuclei of the mononuclear cells vary from ovoid and vesicular to hyperchromatic, and there is often some resemblance to those of cells seen in chondroblastoma. These giant cells are seldom numerous and are not evenly distributed. The cells in the myxochondroid matrix are stellate or spindle-shaped with long cytoplasmic processes. While the matrix is basophilic and has a superficial resemblance to cartilage, true hyaline cartilage differentiation is not seen [2]. One third of the chondromyxoid fibromas are found in the proximal tibia with the others distributed in the distal tibia, proximal and distal femur, flat bones, tarsals, and the other small bones of the hand or foot [3–11]. The case in this report occurred as a surface lesion of the distal metaphysis of the ulna as a focal cortical lytic lesion with expansile remodeling.

I. F. Abdelwahab Icahn School of Medicine at Mount Sinai, New York, NY, USA M. J. Klein (*) Pathology and Laboratory Medicine, Weill Cornell School of Medicine, New York, NY, USA e-mail: [email protected] M. J. Klein Department of Pathology and Laboratory Medicine, Hospital for Special Surgery, New York, NY, USA

Case history A healthy 41-year-old woman presented with gradually increasing pain in the inner part of the forearm just proximal to the wrist. Clinical examination revealed a dorsal fullness with tenderness proximal to the styloid process of the ulna. The range of motion was normal with no evidence of inflammatory

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Fig. 1 Antero-posterior oblique and lateral views of the distal part of the left ulna. The images reveal a 3-cm oval radiolucent lesion in the medulla of the distal metaphysis with cortical scalloping and marginal sclerosis

Fig. 2 a Axial T1W and FSE T2W fat-saturated images. b Coronal T1W and T2 Flash 3D images. MRI reveals an oval, eccentric metaphyseal surface lesion parallel to the long axis of the bone with focal cortical defect and intramedullary extension. It has an isointense signal on T1W images and heterogeneous highintensity signal on T2W images

signs. Radiographs revealed a 3-cm oval, eccentric, radiolucent lesion on the surface of the distal metaphysis of the ulna parallel to the long axis of the bone, with a well-defined, minimally sclerotic, lobulated margin. There was no matrix calcification or cortical expansion. In short, the findings were suggestive of a benign bone tumor (Fig. 1). MRI showed a well-defined elongated focus of abnormal signal on the dorsolateral aspect of the distal ulna with focal cortical involvement without intramedullary extension. The MRI findings were non-specific (Fig. 2), but suggested surface lesions of cartilaginous origin, such as juxtacortical chondroma or low-grade juxtacortical chondrosarcoma. At surgery the periosteum was intact and there was no extraperiosteal soft tissue mass. Biopsy confirmed the diagnosis of surface chondromyxoid fibroma of the distal ulna (Figs. 3, 4). The patient was referred for definitive surgery.

Fig. 3 Low-power magnification demonstrates myxoid areas with gray– blue background in which the cellularity is lower than in the pink areas bordering them. The typical lobulated appearance is somewhat masked by the rather scant quantity of the biopsy sample (×40)

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Fig. 4 Higher magnification contrasts myxochondroid areas (upper and lower right side) with more cellular areas bordering these (center and left)

Discussion Chondromyxoid fibroma comprises less than 1 % of benign bone tumors [9]. While it has been reported at many skeletal sites, its highest incidence by far is in the bones of the lower extremity, particularly the tibia. We reviewed the English

literature to identify the incidence, site, distribution, clinical information, and treatment and follow-up of chondromyxoid fibromas involving the ulna, including 10 large series and 2 relevant case reports (Table 1) [3–15]. The total number of CMFs published was 744; of these, the total incidence in the ulna was 2.82 % with variation in individual series ranging from 0 % to 3.88 %. Adequate clinical information (Table 1) was provided in only 4 cases in which the tumors affected the proximal ulna [4, 13, 14]. Three of these presented with a pathological fracture, which may not be of statistical significance, but is an unusual presenting feature for chondromyxoid fibromas. There were 22 published cases of chondromyxoid fibroma involving the ulna; 12 of these were at the proximal end [4–6, 9, 13, 14]. All cases that we reviewed with clinical information were metaphyseal in location. Only 1 case was specifically reported at the distal ulna [9]. The anatomical distribution was not mentioned in the remaining 9 cases [3, 6]. The juxtacortical variant of chondromyxoid fibroma is a recently recognized subtype that tends to affect individuals of a slightly older age group than the more usual central or eccentric variants, and tends to have distinctive intralesional calcifications [1]. None of the previously reported ulnar cases had been reported as

Table 1 Clinical details of 26 cases of chondromyxoid fibromas of the ulna (includes the 4 cases from our own series) Reference

Number of cases Location in ulna

Symptoms

Treatment

Follow-up

Lersundi et al. [12]

1

Unknown

Not mentioned

Curettage with allograft

Not mentioned

Beggs and Stoker [6] Feldman et al. [3] Rahimi et al. [5] Chen et al. [9]

1 7 1 7

Not mentioned Not mentioned Not mentioned Not mentioned

Not mentioned Not mentioned Not mentioned Not mentioned

Not mentioned Not mentioned Not mentioned Not mentioned

Schajowicz [8]

2

Unknown Unknown Proximal Proximal (6) Distal (1) Proximal

Curettage

Not mentioned

Dahlin [15]

1

Proximal

Not mentioned

Not mentioned

Lettin [13]

1

Proximal

Seth and Rao [14]

1

Proximal

Klein et al., present study

4

Proximal (2) Distal (2)

Pathological fracture in one patient Pain lasting 1 year in the second patient Pathological fracture at the level of the coronoid process of the ulna Spontaneous pathological fracture in a tumor of the epiphysis with cavitation in a 54-year old man Traumatic pathological fracture in a tumor in the epiphysis with cavitation in a 30-year-old man Not reported (personal series) This case report and a second, large distal ulnar tumor with marked cortical expansion, but without pathological fracture or periosteal bone formation

Curettage with bone graft Bony union, normal wrist function

Curettage with bone graft Bony union, normal wrist function

Curettage with bone graft. Healing (both) Curettage (1) Healing Curettage with bone Healing graft (2)

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were distal in location; these are the only cases with available clinical information and imaging, and in addition, the case that we report here arose as a surface lesion. A high percentage (75 %) of CMFs of the proximal ulna presented with pathological fractures. Acknowledgments The authors thank Laraine Tursi, MLS, for her help in preparing the manuscript. Conflict of interest The authors declare that they have no conflict of interest.

Fig. 5 Anteroposterior and lateral views of the distal ulna (second case) demonstrating a radiolucent ulnar lesion occupying the medulla of the metaphysis, epiphysis, and metadiaphysis with marked expansion and cortical thinning due to endosteal scalloping. There is no evidence of pathological fracture or periosteal bone formation

being this subtype, although Schajowicz reported 3 cases of chondromyxoid fibroma with a primarily intracortical distribution [8]. In our own unpublished series of 70 CMFs 4 cases involved the ulna: 2 at the proximal end and the other 2 at the distal end of the ulna, for an incidence of 5.71 %. Although this figure is higher than the upper end of the range found in the reported literature, since many of the cases in the series are outside consultations, there is obvious referral bias in the numbers. One of our 2 cases at the distal ulna is the subject of this report. The second case, received as a consultation, was operated upon in our medical center. Roentgenographs performed at surgery revealed a large expansile lesion of the distal ulna occupying and destroying the medulla of the metaphysis, epiphysis, and metadiaphysis with a welldefined proximal margin. The cortex, though thinned, was intact with no evidence of permeation or soft tissue extension. There were no matrix calcifications or periosteal bone formation (Fig. 5).

Conclusion We reviewed the 22 cases of chondromyxoid fibroma of the ulna reported in the literature. The exact anatomical site of the tumor was reported in 13 cases. Twelve of these cases were specifically reported in the proximal ulna with only 1 case found in the distal ulna. Two of our 4 cases involving the ulna

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