A clinicopathologic study of 12 neuroendocrine tumors arising in the thymus

Study objectives: To determine whether the new classification system for thymic carcinoid tumors/neuroendocrine carcinomas provides prognostic data, and to study the presentation, diagnosis, treatment, and prognostic factors of these rare tumors. Design: Retrospective analysis. Setting: Royal Brompton Hospital, London, UK. Results: Eight men and four women with a median age of 58 years. Complete excision was possible in nine patients. Postoperative staging revealed two stage I tumors, two stage 11 tumors, three stage III tumors, one stage IVA tumor, and four stage IVB tumors. All tumors demonstrated the histopathologic features of neuroendocrine tumors, which were confirmed by positive immunohistochemical staining for chromogranin A in 11 of 12 tumors and for CD56 in 12 of 12 tumors, and the presence of dense core granules on ultrastructural analysis in 9 of 9 tumors. All 12 tumors did not stain positively for somatostatin receptors. Three tumors were grade 1, six cases were grade 2, and three cases were grade 3. Follow-up was available in all patients. One patient died I month postoperatively. Distant metastasis developed in nine patients (82%). Local recurrence was evident in six patients, of whom five had not received postoperative radiotherapy. Seven patients died of distant metastasis (22 to 83 months after surgery). Two are alive and disease-free (at 67 and 81 months), and two are alive with disease (at 60 and 86 months). Conclusions: Neither grading as neuroendocrine carcinomas nor any individual histologic parameter showed a significant association with prognosis. Initial aggressive treatment, including complete surgical excision and adjuvant radiotherapy, appears to offer the best hope for prolonged survival. Adjuvant chemotherapy also should be considered, since the incidence of distant relapse is high.