[Epiphyseal tumors]

Epiphyseal enchondroma masking as osteoid osteoma: a case report

Background

Enchondromas originating in the epiphyses of long bones are rare and epiphyseal osteoid osteomas are also uncommon. Diagnosis can become elusive when enchondromas or osteoid osteomas occur in atypical locations and present with nonspecific clinical and imaging characteristics.

Case presentation

We report a case of epiphyseal enchondroma of the left proximal femur in a 15-year-old girl with a 2-month history of left lower extremity pain. Preoperative CT displayed thickened cortex in the anterior surface of the left proximal femur with specks of calcification and inhomogeneity of the adjacent bone marrow cavity. She was diagnosed with osteoid osteoma. Postoperative pathological examination of surgically excised specimens revealed a diagnosis of enchondromas.

Conclusions

Our case highlights that enchondroma should be considered in lesions of the epiphysis.

Epiphyseal Ewing Sarcoma in a skeletally mature patient: A case report and review of the literature

While Ewing sarcoma of bone is the second most common primary osseous malignancy in childhood where it typically involves the diaphysis or metadiaphyses of long bones of skeletally immature patients, primary epiphyseal involvement of the long bone in skeletally mature patients is rare with no cases reported in the literature to our knowledge, rendering this case the first of its kind.

We present the first case of primary Ewing Sarcoma of the epiphyses of the long bones in a skeletally mature 20-year-old male patient. The patient initially presented with left knee stiffness and pain that was empirically treated with non-steroidal anti-inflammatory medications. His pain progressed despite treatment. An x-ray of the left knee was obtained 5 months later demonstrating an irregular lucent lesion in the medial femoral condyle. A subsequent MRI revealed an enhancing lesion in the medial femoral condyle, and when biopsied it was consistent with Ewing sarcoma (positive for EWSR1gene rearrangement by fluorescence in situ hybridization). The lesion was resected surgically, and the patient underwent neoadjuvant chemotherapy with a good clinical outcome.

Tibial tuberosity lesions

Lesions of the tibial tuberosity are very rare but often present a diagnostic dilemma due to their unusual location and appearances. Although some pathologies affecting this region are commonly seen elsewhere in the skeleton, they may have atypical imaging appearances and morphological characteristics when present at the tibial tuberosity. The present review describes the developmental stages of the tibial tuberosity, explaining why this area is prone to degenerative tractional changes and injury, and also highlights various pathologies including benign and malignant osseous lesions and trauma/degenerative related abnormalities.

Ewing's sarcoma/primitive neuroectodermal tumor of the proximal humeral epiphysis

Ewing's sarcoma/primitive neuroectodermal tumor (ES/PNET) of bone is a rare childhood tumor most commonly located in the metadiaphysis. In skeletally immature patients, lesions of the epiphysis are rarely malignant, with the most common diagnosis being chondroblastoma. This article presents a case of ES/PNET of the proximal humeral epiphysis in a 12-year-old boy. To the authors' knowledge, this is the first reported case of epiphyseal ES/PNET confirmed with molecular testing. Radiographs of the patient's painful shoulder showed a well-defined lytic lesion within the humeral epiphysis. Magnetic resonance imaging suggested a chondroid tumor with surrounding edema. Based on the imaging characteristics, the patient's age, and the lesion's location, a preliminary diagnosis of chondroblastoma was made. A trochar biopsy of the lesion demonstrated a small, round, blue cell tumor on frozen section. Subsequently, immunohistochemical staining was uniformly positive in a membrane pattern for CD99, and molecular diagnostic testing demonstrated a EWSR1/FLI1 fusion transcript, confirming the pathologic diagnosis of ES/PNET. Although metadiaphyseal locations for ES/PNET are most common, this case adds to previously reported cases of epiphyseal ES/PNET, suggesting that the diagnosis be considered for pediatric epiphyseal tumors. This case also demonstrates why following rigorous oncologic treatment algorithms by obtaining a limited trochar biopsy, even in the case of a confident radiographic diagnosis, is critically important; the biopsy results can lead to a major change in treatment and avoid contamination of a larger area of soft tissue and bone.

Epiphyseal Ewing Sarcoma

Ewing sarcoma is the second most common pediatric malignant bone neoplasm after osteosarcoma. Ewing sarcoma comprises “small, round, blue-cell” tumors thought to arise from neural crest cells. The authors report the case of a 14-year-old boy that presented with a nonpainful circumscribed lesion. The radiographs showed a lytic lesion at the tibial epiphysis with a large soft tissue mass, best depicted in the magnetic resonance imaging scan that suggested an aggressive lesion. A needle biopsy of the lesion was performed. The diagnosis of Ewing sarcoma was made based on microscopic, immunohistochemical, polymerase chain reaction, and fluorescence in situ hybridization. This is the third case report about a primary epiphyseal Ewing sarcoma and the fist one with molecular confirmation.

Solitary epiphyseal enchondroma of the proximal femur in a 23-month-old girl

A 23-month-old girl was referred to us because of a right leg limp for 10 days that had not improved despite anti-inflammatory treatment and that did not show signs of infection. Upon examination, gait was in abduction and external rotation of the hip. Plain radiographs showed a solitary lucent lesion of the posteroinferior two thirds of the epiphysis that was hyperintense on T2-weighted magnetic resonance scanning images. We approached the proximal femoral epiphysis using the "trapdoor" technique and excised the lesion by curettage and iliac crest graft. Histologically, the lesion was diagnosed as an enchondroma. We discuss the main causes of lucent epiphyseal lesions in children. Finally, we review the literature on previous reports of patients with solitary epiphyseal enchondromas.

STUDY TYPE

Case report.