Temporal Bone Histopathology Case of the Month
Radiation-Induced Squamous Cell Carcinoma of the External Auditory Canal*Min-Tsan Shu, *Hung-Ching Lin, *Jehn-Chuan Lee, and †Be-Fong Chen
Departments of *OtolaryngologyYHead and Neck Surgery, and ÞPathology, Mackay Memorial Hospital, Taipei, Taiwan, Republic of ChinaRadiation treatment of nasopharyngeal carcinoma (NPC) may induce malignancy in the external ear or mastoid (1Y4), occurring with an incidence of approximately 0.15% (1). Modified criteria (1) for thediagnosis of radiation-induced malignancy include a previous history of irradiation, followed by development of a new malignancy in the radiation field diagnosed no less than 2 years after theradiotherapy and which is proven to differ histologically from the original malignancy. En bloc resection including lateral subtotal or total tem-
poral resection is usually recommended for removal of aprimary ear malignancy. CASE REPORT A 65-year-old man with a diagnosis of stage T2bN3aM0 NPC (Fig. 1) had been treated with concurrent chemoradiation therapy. The radiation dose was 8,070 cGy to the grosstumor in the nasopharynx. Left ear discharge was noted occasionally after concurrent chemoradiation therapy. However, 5 years after treatment, the patient presented with bloody discharge andgranulation in the left external auditory canal, which had been present for 5 months. High-resolution computed tomography showed a soft tissue mass without bony destruction in the left external auditory canal.Histopathologic examination
FIG. 1. A, Original nasopharyngeal tumor showing features of a nonkeratinizing carcinoma, undifferentiated type. Cells grow in irregular nests (black arrow). The stromahas a dense lymphoplasmacytic infiltrate (asterisk) (hematoxylin and eosin; original magnification, Â100). B, Tumor cells are polygonal, having vesicular nuclei with distinct nucleoli (hematoxylin...