Columnar Cell Thyroid Carcinoma: A Heterogeneous Entity Demonstrating Overlap Between Papillary Thyroid Carcinoma and Follicular Neoplasms

BACKGROUND

Columnar cell papillary thyroid carcinoma (CC-PTC) is a morphologic subtype of papillary thyroid carcinoma with a variable prognosis. It is characterized by neoplastic thyroid follicular-derived cells with pseudostratified columnar morphology arranged in papillary or follicular structures with supranuclear or subnuclear vacuoles. The molecular profile of this subtype has only recently come under scrutiny, with mixed results. The aim of this study is to further explore the morphologic, immunohistochemical, and genetic profile of CC-PTC, as well as to correlate these features with clinical outcomes.

METHODS

CC-PTC cases were identified from 3 institutions. Immunohistochemistry (ER, CDX2) and molecular testing (DNA and RNA sequencing) were performed. Clinicopathologic parameters and patient outcomes were recorded.

RESULTS

Twelve cases (2006-2023) were identified, all in adults (age 45-91). Two presented with disease outside the thyroid gland (neck and mediastinum) and two presented with distant metastasis. Four were high-grade differentiated thyroid carcinomas (necrosis or mitoses), one of which died of disease. Four were noninvasive or minimally invasive, one of which locally recurred. Three patients had lymph node metastases. ER and CDX2 were positive in 73% and 50%, respectively. Pathogenic mutations were found in TERT promoter (n = 3), RAS (n = 2), ATM, NOTCH1, APC, and ESR1, along with cases bearing AGK::BRAF fusion (n = 1), BRAF VE1 expression (n = 1), and NF2 loss (n = 1).

CONCLUSIONS

This study represents the largest molecularly defined cohort of non-oncocytic thyroid carcinomas with columnar cell morphology. These tumors represent a genetically and behaviorally heterogeneous group of neoplasms, some of which have RAS-like or follicular neoplasm-like genetics, some of which have BRAF-p.V600E-like or classic papillary thyroid carcinoma-like genetics, and some of which remain unclear. Noninvasive or minimally invasive tumors showed an indolent course compared to those with angioinvasion, gross extrathyroidal growth, or high-grade morphology. Consideration could be given to reclassification of this neoplasm outside of the subtyping of papillary thyroid carcinoma in light of its genetic diversity, distinct morphology, and clinical behavior more closely aligned with follicular thyroid neoplasms.

Brain metastases of papillary thyroid carcinoma origin are derived from aggressive histologic variants and demonstrate similar adverse morphology in the metastatic lesion

BACKGROUND

Distant metastases of papillary thyroid carcinoma are exceedingly rare. We analyzed all cases of brain metastases of papillary thyroid cancer at our institution and performed a literature review over the past ten years to identify histologic and molecular features of primary and metastatic tumors.

METHODS

Following institutional review board approval, the entire pathology archives at our institution were searched for cases of papillary thyroid carcinoma metastatic to brain. Patient demographics, histologic features of both primary and metastatic tumors, molecular information, and clinical outcomes were investigated.

RESULTS

We identified 8 cases of metastatic papillary thyroid carcinoma to brain. The average age at time of diagnosis of metastases was 56.3 years (range: 30-85). Average time from diagnosis of primary thyroid cancer to brain metastasis was 9.3 years (range: 0-24 years). All primary thyroid carcinomas demonstrated aggressive sub-types which were correspondingly seen in brain metastases. Next-generation sequencing revealed the most common mutations were identified in BRAFV600E, NRAS, and AKT1 with one tumor harboring a TERT promoter mutation. Six out of eight patients were deceased at the time of study with an average survival time of 2.3 years (range: 0.17-7 years) following diagnosis of brain metastasis.

CONCLUSIONS

Based on our study, it is highly unlikely that a low-risk variant of papillary thyroid carcinoma will metastasize to the brain. Therefore, careful and accurate reporting of the papillary thyroid carcinoma subtype in primary thyroid tumors is warranted. Certain molecular signatures are associated with more aggressive behavior and worse patient outcomes and next-generation sequencing should be performed on metastatic lesions.

Columnar cell papillary thyroid carcinoma prognosis: findings from the SEER database using propensity score matching analysis

BACKGROUND

Columnar cell papillary thyroid carcinoma (CCPTC) is a rare variant of papillary thyroid carcinoma (PTC), whose prognosis, as defined by the American Thyroid Association (ATA) guidelines, is considered poor, although available evidence is insufficient for reliable assessment. This study aimed to investigate the CCPTC prognosis using the Surveillance, Epidemiology, and End Results (SEER) database.

METHODS

Data of thyroid cancer patients, recorded from 2004 to 2013, were extracted to assess the CCPTC prognosis. All-cause and cancer-specific mortality rates associated with thyroid cancer types were evaluated using the Kaplan-Meier method and Cox proportional hazards regression. Propensity score matching analysis was used to adjust for potential confounders.

RESULTS

Cancer-specific mortality per 1000 person-years was higher for CCPTC than for classic papillary thyroid cancer (CPTC) and follicular thyroid cancer (FTC). The multivariate Cox regression model revealed that the cancer-specific and all-cause mortality rates were higher for CCPTC than for CPTC but not FTC. However, propensity score matching analysis demonstrated a significantly lower survival for CCPTC than for both CPTC and FTC.

CONCLUSIONS

Our findings provide evidence to support the poor prognosis associated with CCPTC. These findings may serve to improve the diagnosis of CCPTC, provide reliable reference data for clinical use, and increase the comprehensiveness of current guidelines.

Columnar cell lesions and pseudoangiomatous hyperplasia like stroma: is there an epithelial-stromal interaction?

The significance of association between cancer and its microenvironment has been increasingly recognized. It has been shown in animal models that interaction between neoplastic epithelial cells and adjacent stroma can modulate tumor behavior. Carcinoma associated stromal cells can transform normal epithelial cells into neoplastic cells. In breast, columnar cell lesions are non-obligate precursors of low grade ductal carcinoma in situ. Columnar cell lesions can be seen intimately associated with PASH-like-stroma, a lesion we termed as CCPLS. Our aim is to investigate epithelial-stromal interactions in CCPLS and compare them to PASH without columnar cell lesions in breast core needle biopsies. Normal terminal duct lobular unit (TDLU) epithelium was seen in association with columnar cell lesions as well as PASH. Eight (8) cases of each category were examined by a panel of immunostains: CD117 (C-kit), CD34, CD105, bFGF, AR, ER-beta, MIB-1. We observed a markedly decreased expression of c-kit in columnar cell lesions compared to TDLU-epithelium. CD105 showed a quantitative increase in activated vessels in CCPLS compared to PASH. A subset of CCPLS and PASH were androgen receptor positive. A strong nuclear positivity for ER-beta is observed in the epithelium and stroma of all CCPLS cases. We conclude that (1) activated blood vessels predominate in CCPLS; (2) A molecular alteration is signified by c-kit loss in columnar cell lesions; (3) ER-beta and androgen receptor positivity indicate CCPLS are hormonally responsive lesions. Our study suggests an intimate vascular and hormone dependent epithelial-stromal interaction exists in CCPLS lesions.

Flat Epithelial Atypia of the Breast

Lesions of the breast characterized by enlarged terminal duct lobular units lined by columnar epithelial cells are being encountered increasingly in breast biopsy specimens. Some of these lesions feature cuboidal to columnar epithelial cells in which the lining cells exhibit cytologic atypia. The role of these lesions (recently designated "flat epithelial atypia" [FEA]) in breast tumor progression is still emerging. FEA commonly coexists with well-developed examples of atypical ductal hyperplasia, low-grade ductal carcinoma in situ, lobular neoplasia, and tubular carcinoma. These findings and those of recent genetic studies suggest that FEA is a neoplastic lesion that may represent a precursor to or the earliest morphologic manifestation of ductal carcinoma in situ. Additional studies are needed to better understand the biologic nature and clinical significance of these lesions.

Comparative cytokeratin expression in the different cell types of salivary gland mucoepidermoid carcinoma

Mucoepidermoid carcinoma is the most common malignant salivary gland tumor, composed of several different cell types, with controversial histogenesis. The aim of this study was to assess the expression of cytokeratins in mucoepidermoid carcinoma, comparing to cytokeratin expression in normal salivary glands, in order to establish a possible correlation between tumor cells immunostaining and mucoepidermoid carcinoma histogenesis and differentiation. Eighty cases of salivary gland mucoepidermoid carcinoma were immunohistochemically examined with the use of antibodies against cytokeratins 6, 7, 8, 13, 14, 18, and 19. Cytokeratin expression varied according to the cellular type: squamous cells presented high expression of cytokeratins 6, 7, 8, 14, 18, and 19; intermediate and mucous cells of cytokeratin 7; clear and columnar cells of cytokeratins 6, 7, 8 and the latter also expressed cytokeratin 18. Cytokeratin 13 expression was low in all cell types. Cytokeratin immunoexpression in mucoepidermoid carcinoma was variable according to the cellular type; but regardless of the cellular type studied, cytokeratins 7 and 13 were, respectively, constantly high and low expressed. The immunoprofile of the normal salivary glands was variable according to the component but, in general, cytokeratin profile in mucoepidermoid carcinoma showed similarity to the immunoexpression on the excretory duct unit of normal salivary glands.