Concomitant medullary thyroid carcinoma with paraganglioma-like pattern and papillary thyroid carcinoma

Abstract

Summary A 74-year-old man was referred to the Endocrinology Unit because of multinodular goiter. The dominant nodule (1.7 × 1.9 × 2.4 cm), at the medium-superior third of the left lobe, was inhomogeneously hypoechoic, with irregular margins, macrocalcifications and intranodular vascularization. Fine-needle aspiration biopsy (FNAB) was performed. The cytological diagnosis was TIR 2, benign, according to the 2013 Italian thyroid cytology classification system. Moderately high serum calcitonin (s-Ct) (61.5 pg/mL, n.r. 0–7.5) and normal CEA were detected. The Ct level in FNAB wash-out fluid (Ct-FNAB) was 1450 pg/mL. Based on s-Ct and Ct-FNAB levels, patient underwent total thyroidectomy. Macroscopically, a dominant circumscribed nodule of 2 ecm was described; the histological and immunohistochemical features identified medullary thyroid carcinoma (MTC) with paraganglioma (PG)-like pattern positive for Ct, CEA and chromogranin and negative for S-100 sustentacular cells (SC). Moreover, papillary carcinoma of 3 mm in the right lobe was also associated. No areas of hyperaccumulation of the tracer were documented at Ga68 PET/CT. No RET-proto-oncogene mutations were found. Post-surgery s-Ct levels were within normal range (4 pg/mL). Two years after thyroidectomy, the patient is still disease-free. We reported a case of sporadic and rare variant of MTC: this is the ninth described case of PG-like MTC. In this case, cytologically benign, the clinical suspicion arose from high Ct values at FNAB wash-out fluid. Even if clinical behavior of this variant seems indolent, additional studies are necessary to understand prognoses and predictive factors. Learning points: Several unusual histological variants of medullary thyroid carcinoma (MTC) have been described such as spindle cell, giant cell, clear cell, melanotic, squamous, angiosarcoma-like variants; even rarer is the paraganglioma (PG)-like pattern. We here describe a case of medullary PG-like thyroid carcinoma in a 74-year-old man. This is a rare histological variant of MTC hardly diagnosed by cytology, since immunohistochemical investigations are necessary. Measurement of calcitonin both in serum and in wash-out fluid from fine-needle aspiration could be an additional tool for an early and non-invasive identification of these variants.

Diagnostic Utility of INSM1 in Medullary Thyroid Carcinoma

“…The prototypical or classic MTC displays solid, trabecular, and insular patterns. 1 There are many other histologic types, including papillary, pseudopapillary, follicular (tubular/glandular), 24,25 spindle cell, giant cell, clear cell, oncocytic, melanotic, squamous, amphicrine, paraganglioma like, 26,27 angiosarcoma like, encapsulated, and small cell. 28-30 The differential diagnosis of prototypical or classic MTC includes poorly differentiated carcinoma, solid variant of PTC, follicular neoplasm, and Hurthle cell neoplasm with solid patterns.…”

The diagnostic utility of INSM1 and GATA3 in discriminating problematic medullary thyroid carcinoma, thyroid and parathyroid lesions

“…Medullary thyroid carcinoma (MTC), a well-differentiated neuroendocrine tumor of the thyroid gland, is derived from the parafollicular calcitonin-producing cells (C-cells). It constitutes 5-8% of all thyroid malignancies [3,4], so due to the limited numbers of patients, its study is rather difficult. In addition, no agreement has been reached as regards the classification of its cytoarchitectural patterns [5].…”

Medullary thyroid carcinoma a relatively uncommon entity: A case report

“…In all type of MTC the average survival varied from 61% to 75% for 10 years. 3 The majority of MTCs are sporadic, while heritable incidence includes 25% to 30% of cases, which is associated with multiple endocrine neoplasia (MEN) 2A, MEN 2B, or with the familial medullary thyroid carcinoma syndrome. 1,4 Genetic forms of MTC often present as multifocal disease is caused by autosomal dominant mutations of the RET proto-oncogene with incomplete penetrance with few cases being reported to have new spontaneous mutations of the gene.…”