Cytomorphologic features of diffuse sclerosing variant of papillary carcinoma of the thyroid - A report of two cases in children

BACKGROUND: Diffuse sclerosing papillary carcinoma (DSPC), a variant of papillary carcinoma of thyroid, needs to be differentiated from classical papillary carcinoma and other variants. This variant is characterized by diffuse involvement of one or both thyroid lobes showing such histologic features as prominent sclerosis, an intense lymphocytic infiltrate, numerous psammoma bodies and squamous metaplasia together with the characteristic cytoarchitectural pattern of classical papillary carcinoma. Histologic and immunohistochemical features have been described in previous publications. Although cytologic features of several variants of papillary carcinoma have been described pueviously, those of DSPC have not been widely published. The present report is on the cytomorphologic pattern of DSPC in two children, further highlighting the special features. CASES: A boy, aged 11 years, presented with diffusely nodular, firm enlargement of the thyroid gland with many palpable lymph nodes, and a girl, aged 12 years, presented with diffusely nodular, firm enlargement of the left lobe with a prominent nodule on the lower pole. Fine needle aspiration biopsy (FNAB) smears stained with hematoxylin and eosin showed numerous psammoma bodies, many lymphocytes, metaplastic squamous cells and absent stringy colloid together with epithelial cells showing classical features of papillary carcinoma, such as nuclear grooves, intranuclear inclusions and papilloid structures. Histologic examination of the thyroidectomy specimens showed features of diffuse sclerosing variant of papillary carcinoma. CONCLUSION: A diagnosis of DSPC should be considered when a combination of clinicocytologic features consisting of numerous psammoma bodies, lymphocytes, squamous metaplasia and absence of stringy colloid are noted with otherwise typical cytoarchitectural features of papillary carcinoma in FNAB smears obtained from diffusely nodular, firm thyroid enlargement.