Variants of papillary thyroid carcinoma: multiple faces of a familiar tumor

Abstract

Classically characterized by its papillary appearance, papillary thyroid carcinoma is the most common malignant neoplasm of the thyroid. Several variants of papillary carcinoma have been described considering size (microcarcinoma); nature of the tumor boundaries (encapsulated); architecture (follicular, macrofollicular, cribriform-morular, solid, micropapillary); cellular characteristics (tall cell, columnar, oncocytic, clear cell, hobnail); additional tumor components (papillary carcinoma with focal insular component, papillary carcinoma with spindle and giant cell carcinoma, papillary carcinoma with squamous cell carcinoma, papillary carcinoma with mucoepidermoid carcinoma); stromal features (papillary carcinoma with fasciitis like stroma); or a combination of the abovementioned characteristics (diffuse sclerosing, Warthin-like). Although most variants do not pose any diagnostic problems; some histological variants can be challenging to the pathologist and some are of clinical significance, because of prognostic implications or accompanying clinical conditions. It is not rare to find a papillary carcinoma showing characteristics of more than one variant. For example: an individual tumor can show hobnail features and present as a microcarcinoma; another case can show solid architecture and clear cytoplasm. In such cases, it is more important to comment on clinically relevant morphological characteristics of the tumor, rather than religiously trying to classify an individual tumor into a particular variant. In this review, pathologic and clinical features of papillary carcinoma variants are summarized.

Cytopathology of Solid Variant of Papillary Thyroid Carcinoma: Differential Diagnoses with other Thyroid Tumors

“…SVPTC is a rare PTC subtype, initially described by Carcangiu et al [9] in 1985 with a reported frequency of 3% [2]. In the current study, SVPTC constituted 2.8% of the total PTC cases.…”

“…Solid/trabecular variant of PTC (SVPTC) is relatively rare, constituting 3% of all adult-onset PTCs [2]. Initially thought to occur preferentially in children, especially after radiation exposure, SVPTC has now been reported even in adults, irrespective of radiation history [3-5].…”

“…Papillary thyroid carcinoma (PTC) is the most common malignant thyroid neoplasm (80%) and has about 15 variants described in the latest World Health Organisation (WHO) classification [1, 2]. Solid/trabecular variant of PTC (SVPTC) is relatively rare, constituting 3% of all adult-onset PTCs [2].…”

H-scan analysis of thyroid lesions

“…Certain chemical and molecular changes in the nucleus and cell morphology are seen in papillary thyroid carcinoma variants, and these changes have been characterized by scattering properties. [12][13][14] In a population-based study by Smith-Bindman et al, 15 microcalcifications were associated with 38.2% of malignant nodules and 5.4% of benign nodules. Models for classifying microcalcifications as elastic scatterers under ultrasound have been studied previously.…”

Papillary microcarcinoma of the thyroid: a review

“…Pathologically, microPTCs do not exhibit different morphological characteristics compared to classical papillary carcinomas [11]. They are likely to be located near the capsule of the thyroid gland and are non-encapsulated.…”