Pediatric Chondromyxoid Fibroma-Like Osteosarcoma

Cement arthrodesis of the knee using combined intramedullary nail, plate and screws after wide excision in huge chondromyxoid fibroma of proximal tibia, a case report

Introduction and importance

Chondromyxoid fibroma is a rare benign cartilaginous neoplasm, a mixture of benign cartilage and fibrous and myxoid tissue. It usually affects young people, commonly in the second and third decades of life with male being predominant. Differential diagnosess in chondromyxoid fibroma, are giant cell tumor, bone cyst, enchondroma, osteoblastoma, and low-grade chondrosarcoma.

Case presentation

We present a case of an 18-years-old male, with chief complaint of pain on the right knee since 3 year ago with an increasing size reaching diameter of 55 cm within three years. The radiograph and MRI revealed lytic blastic expansile multiloculated lesion, with wide transitional zone, and periosteal reaction on the epymetadiaphyseal part of right proximal tibia. The surgical procedure was performed consist of wide excision, reconstruction by cement knee arthrodesis using Kuntscher-nail, dynamic compression plate, bone cement and gastrocnemius flap.

Clinical discussion

After 3 months of surgery follow-up, there was no sign of recurrence, the patient walked partially weight bearing with a crutch. In 1 years post operative follow up, the Muscukoskeletal Tumor Society Scoring (MSTS) was 80%. There was no sign of recurrence.

Conclusion

In cases with large tumor size, wide excision with bone and soft tissue reconstructive surgery is required as mechanical and biological reconstruction. The cement arthrodesis provides a faster duration of surgery, lower risk of infection, and good functional outcome.

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Chondromyxoid fibroma is a rare benign cartilaginous neoplasm, mixture of benign cartilage and fibrous and myxoid tissue

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There are no specific recommendation in management of chondromyxoid fibroma due to limited published article with chondromyxoid fibroma.

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The mechanical and biological reconstruction are very important during reconstructive surgery.

Chondromyxoid Fibroma-Like Osteosarcoma in a 13 Years Old Girl: A Report of a New Case

Osteosarcoma (OS) is the most common primary non hematopoietic malignant tumor of bone with a strict histologic definition: the presence of unequivocal osteoid produced by neoplastic cells. Rare variants displaying low-grade histological features have been described; among which chondromyxoid fibroma-like (CMF-OS) is the rarest. However, despite its bland morphology; CMF-like OS has an aggressive clinical behavior and a poor prognosis. To the best of our knowledge, only 3 cases of CMF-OS have been previously reported in children. Because of its atypicality and scarcity; misdiagnosis is more likely to occur. Herein we describe a new case of CMF-OS in a 13 years old girl with fatal outcome. Diagnosis was based on focal malignant bone formation and correlation with imaging studies. The aim of the present case presentation is to raise awareness of this rare entity and to highlight the challenging diagnosis.

Chondromyxoid fibroma-like osteosarcoma: a case series and literature review

BACKGROUND

Chondromyxoid fibroma-like osteosarcoma (CMF-OS) is an exceedingly rare subtype of low-grade central osteosarcoma (LGCO), accounting for up to 10% of cases and making it difficult to diagnose. CMF-OS is frequently misdiagnosed on a radiological examination and biopsy, even after the initial operation. Its treatment is a controversial issue due to its low-grade classification and actual high-grade behavior.

CASE PRESENTATION

We retrospectively reviewed the medical charts of more than 2000 osteosarcoma patients between 2008 and 2019; 11 patients with CMF-OS were identified, of which six patients were treated by our institution with complete clinical characteristics, including treatment and prognosis, radiological and pathological features were reviewed. Three males and three females with a median age of 46 (range 22-56) years were pathologically proven to have CMF-OS. The radiological presentation of CMF-OS is variable, thus radiological misdiagnoses are common. However, one must not ignore a malignant radiologic appearance. The most distinctive pathological feature conferring the diagnosis of CMF-OS is the presence of osteoid production directly by the tumor cells under a chondromyxoid fibroma (CMF)-like background. Differential diagnoses based on comprehensive data from CMF, LGCO, chondrosarcoma (CHS), conventional osteosarcoma (COS), etc., are needed. All patients were treated with an operation and chemotherapy, and one patient received additional radiotherapy. Nevertheless, recurrence and metastasis are common in CMF-OS patients. Relatively invasive biological behavior of CMF-OS is against the low-grade classification of this disease.

CONCLUSIONS

It is important to recognize CMF-OS and distinguish it from CMF, CHS, COS and other LGCOs. CMF-OS has a relatively poor prognosis despite its low-grade classification.