Endocrine Abstracts

Introduction: Poorly differentiated thyroid carcinoma (PDTC) and anaplastic thyroid carcinoma (ATC) have been conjectured to arise from well differentiated thyroid carcinoma (WDTC) due to frequently reported synchronous and metachronous occurrence. We demonstrate the simultaneous presence of divergent histological subtypes in a single thyroid gland, with escalating loss of p53 expression in more aggressive variants.

Material and methods: A 60-year-old male with multiple neurofibromas presented with a palpable anterior neck mass, firm and fixed to underlying structures. Hormonal evaluation was conducted to evaluate thyroid function and rule out the presence of a pheochromocytoma, on grounds of unproven von Recklinghausen disease. Ultrasound revealed a hypoechogenic nodule on the left lobe, measuring 5.84×2.81 cm, with peripheral vascularity, which comprised a 2.24×1.28 cm area with suspicious calcifications. Three smaller hypoechogenic nodules with peripheral vascularity, 3.26, 3.18 and 0.83 cm respectively, were also observed. On the right lobe three isoechogenic nodules, 2.19, 1.47 and 0.73 cm, with cystic areas and no remarkable vascularity were noted.

Results: Histopathological examination revealed three foci at the right lobe, with characteristics of predominantly papillary but also follicular carcinoma growth pattern, with infiltrating margins and foci of extrathyroidal extension. At the left lobe two lesions were described, which presented with histologic features of insular and trabecular variant of PDTC. The larger tumor showed foci of anaplastic transition, with diffuse growth pattern, nuclear pleomorphism and areas of necrosis. Both tumors invaded thyroid capsule and displayed extrathyroidal extension reaching the inked surgical margins. Vascular emboli were also identified. Poorly differentiated tumor area appeared with reduced nuclear p53 protein accumulation.

Conclusion: We present a case of progressive decline of p53 expression in multifocal thyroid tumor areas consisting of WDTC, PDTC and ATC histologies, highlighting the possibility that WDTC can progress to PDTC and then ATC through an intricate procedure involving loss of p53.