Primary intraosseous carcinoma

Primary intraosseous carcinomas NOS (PIOC) are malignant epithelial odontogenic neoplasms of the jawbones with no clear benign analog.

Epidemiology

Primary intraosseous carcinomas are rare tumors ^1-4. They occur in a wide age range with the mean in the sixth decade of life. Men are more frequently affected ⁴.

Diagnosis

Primary intraosseous carcinomas are a diagnosis of exclusion and are only diagnosed after other carcinomas in particular primary metastatic carcinomas or extension of oropharyngeal carcinomas have been excluded ^1,2.

Clinical presentation

Clinical symptoms are nonspecific. They might be found incidentally, present with swelling pain or metastatic disease ^1-3.

Pathology

Primary intraosseous carcinomas are malignant epithelial tumors that arise from epithelial remnants of the dental lamina, the odontogenic epithelium from a cyst or other epithelial lesions ^2,3.

Location

Primary intraosseous carcinomas are most often found in the posterior body and ramus of the mandible. Less commonly they are found in the anterior part of the maxilla ².

Microscopic appearance

Histologically primary intraosseous carcinomas have similar features as squamous cell carcinoma ^1-3:

• small sheets, strands or nests of atypical squamous cells
• cellular pleomorphism
• nuclear hyperchromatism
• increased mitotic activity
• no features of ameloblastoma
• rarely significant keratinization

Immunophenotype

Immunohistochemistry helps differentiate primary interosseous carcinomas from carcinomas of other sites ². CK19 positivity suggests origin from odontogenic epithelium ⁵.

Radiographic features

Plain radiograph

The orthopantomogram usually shows a radiolucent lesion. Larger lesions might show cortical perforation and destruction ².

Radiology report

The radiological report should include a description of the following features:

• type location and size of the lesion
• unilocular or multilocular appearance
• relation to the adjacent structures and teeth
• unerupted tooth or tooth displacement

Treatment and prognosis

Management includes radical resection with neck dissection and possibly adjuvant radio and/or chemotherapy ^1-5. Lymph node metastases are common whereas distant metastases are uncommon. Still, the prognosis is poor with a five-year survival rate of less than 40% ^5,6 and a slightly better prognosis in cases originating from cysts ^2,3.

History and etymology

The primary intraosseous carcinoma has been first described by D.Loos in 1913 as central epidermoid carcinoma ⁷.

Differential diagnosis

The differential diagnosis of primary intraosseous carcinomas include the following:

• oropharyngeal carcinoma
• metastatic carcinoma
• odontogenic cysts
• ameloblastoma