dr james c wittig, orthopedic oncologist, new york, new jersey
About Dr. Wittig
Intracortical Osteosarcoma

General Information

  • Intracortical osteosarcoma is an extremely rare type of osteosarcoma that arises within and is usually confined to the cortex of the bone.
  • It is a high grade osteosarcoma that is confined to the cortex of a long bone
  • Intracortical osteosarcoma is very rare and only a handful of cases have been reported.
  • It is often initially misdiagnosed as an osteoid osteoma, bone abscess, non ossifying fibroma, osteoblastoma or adamantinoma until it is biopsied or removed

Clinical Presentation

Signs/Symptoms:

  • Pain, swelling, tenderness, <1 year

Sex Predilection:

  • Possible slight male predilection

Age:

  • 10-30 years

Sites:

  • Diaphysis of femur or tibia are the most common sites

Radiographic Presentation

Plain Radiographs:

  • Intracortical lytic lesion with surrounding sclerosis
  • The junction of the lesion with the normal bone is usually irregular but sharply demarcated
  • Size of lesion is usually between 1 cm to 5 cm
  • Lesion may demonstrate ossification or mineralization within it
  • No intramedullary or soft tissue involvement
  • Minimal or no periosteal reaction or periosteal reaction may appear benign
  • CT may show cortical permeation

Gross Pathology

  • Intracortical, well defined tumor with very thick expanded cortex
  • Irregular borders
  • Thick and expanded cortex
  • Tumor is grey/tan/yellow and gritty from mineralized osteoid or bone production

Microscopic Pathology

  • Highly osteoblastic & sclerotic similar to a conventional osteosarcoma
  • Neoplastic cells when become entrapped in osteoid may appear to normalize and have less nuclear pleomorphism and atypia
  • Residual cortical bone will be entrapped by malignant cells producing osteoid (evidence of malignancy)
  • There may be very small chondrosarcomatous and fibrosarcomatous foci
  • Cartilage production is minimal (as opposed to a periosteal osteosarcoma)
  • Malignant spindle cell tumor producing osteoid
  • Malignant cells have large nuclei, minimal cytoplasm, nuclear pleomorphism, mitoses
  • They appear crowded and haphazard
  • The osteoid is layed down in lace-like manner in between malignant cells

Differential Diagnosis

  • Osteoid Osteoma
  • Brodie's Abscess
  • Osteoblastoma
  • Nonossifying fibroma
  • Eosinophillic Granuloma
  • Osteofibrous Dysplasia
  • Adamantinoma

Treatment

  • En bloc Resection/Limb Sparing Surgery whenever feasible
  • Patients treated by curettage and intralesional procedures have experienced local recurrences according to the literature
  • Efficacy of chemotherapy is uncertain given the small number of cases

Prognosis

  • Metastases to the lungs along with unusual sites of metastases have been reported
  • Exact statistics are unavailable given the small number of patients who have been reported to develop this disease.
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