Mediastinum

Thymic epithelial tumours: histopathological classification and differential diagnosis

“…6 In contrast to thymic carcinomas, thymomas can show a variable and frequently indolent clinical behaviour, but all subtypes are considered malignant. Following complete resection, they have a recurrence rate of around 10% (2% for encapsulated and 20 to 40% for invasive thymomas) with a mean time to recurrence of 6 years (range 1-16 years), 7,8 and a 10-year survival after recurrence of up to 65%. They rarely metastasize (in 1%-2% of cases) and if so, are associated with a poor prognosis.…”

Spindle Cell Neuroendocrine Carcinoma of the Lung

“…[21][22][23] In spindle cell thymomas, epithelial cells tend to form cohesive fascicles and, less frequently, shed singly; they display a finely granular chromatin structure with small nucleoli and pointed, rather than tapered, nuclear ends and usually lack frank cytologic atypia on FNAC samples, sharing with neuroendocrine carcinoma pan-CK positivity, while CK19 is reportedly positive only in thymomas and not in neuroendocrine carcinomas. 18,22,23 The possibility of spindle cell IT was considered, based, again, on the peculiar admixture of mature lymphoplasmacellular elements with fusiform cells. IT may present as a well-circumscribed lesion on CT. 10 Neuroendocrine cell markers appear to be crucial in this last differential diagnosis.…”

“…10 Despite its rarity, it may share with its thymic form a varied cytologic presentation, encompassing forms with a lymphocyte predominance and predominantly epithelial variants, the latter also with spindle cells. [18][19][20][21][22][23] In lymphoepithelial thymoma, the epithelial cells show pale nuclei with prominent nucleoli and are usually intimately admixed with the lymphoid component. Immunocytochemical stain for pan-CK or CK19 may enhance their presence even when this is not apparent on routine cytological preparations.…”