Radiation-induced malignant fibrous histiocytoma in patients with nasopharyngeal carcinoma.

OBJECTIVE

To evaluate the prevalence, 15-year cumulative incidence, time interval, and prognosis of radiation-induced malignant fibrous histiocytoma of the head and neck in long-term survivors of nasopharyngeal carcinoma.

DESIGN

Cohort.

SETTING

Tertiary care hospital.

PATIENTS

Eight long-term survivors of nasopharyngeal carcinoma with malignant fibrous histiocytoma in the maxillary sinus or nasal cavity.

MAIN OUTCOME MEASUREMENT

Survival of postirradiation malignant fibrous histiocytoma in patients with nasopharyngeal carcinoma.

RESULTS

The prevalence of radiation-induced malignant fibrous histiocytoma in long-term survivors of nasopharyngeal carcinoma was 0.38%. The 15-year cumulative incidence was 2.2%. Most tumors occurred in the maxillary sinus and were characterized by spindle-shaped tumor cells with plump nuclei arranged in a whorl or storiform pattern in a fibrous stroma. The mean interval between malignant fibrous histiocytoma and nasopharyngeal carcinoma was 121 months. Local recurrence developed in all cases within 9 months after surgery. Six patients died of disease without distant metastasis within 30 months. Two patients were alive with disease for 20 and 32 months, respectively.

CONCLUSIONS

Radiation-induced malignant fibrous histiocytoma in the head and neck region in long-term survivors of nasopharyngeal carcinoma is rare. It takes a long time to occur after irradiation and is locally invasive with poor prognosis.