Synchronous Thyroid Involvement in Plasma Cell Leukemia Masquerading as Hashimoto's Thyroiditis: Role of Ancillary Cytology Techniques in Diagnostic Workup

Medullary thyroid carcinoma co-existent with Hashimoto's thyroiditis diagnosed by a comprehensive cytological approach

Fine-needle aspiration cytology (FNAC) is a preliminary test for the diagnosis of thyroid lesions. We hereby report a rare case of medullary thyroid carcinoma (MTC) co-existing with Hashimoto's thyroiditis (HT). This case was substantiated with ancillary tests on cytology material to give a novel insight. A 60-year-old female presented clinically with diffuse enlargement of the thyroid, and right-side nodule on ultrasonography. FNAC of the isthmic area showed features of HT, while cytology of right-side nodule displayed sheets of plasmacytoid cells and frequent scattered large bizarre and pleomorphic cells, lymphoglandular bodies and pale eosinophilic material. The differential diagnosis of MTC with co-existent HT or high-grade lymphoma was considered. To establish the diagnosis, serum calcitonin and ancillary studies on aspirated material were carried out. High serum calcitonin (7251 pg/mL), Congophilia on smears, and CD 45-ve; CD56+ve expression of tumor cells on flowcytometric analysis established the diagnosis of MTC over lymphoma. This diagnosis was further confirmed upon histopathology. Ancillary studies on aspirated material established the diagnosis of MTC and excluded the diagnosis of lymphoma. Establishing the correct diagnosis was cardinal in such a scenario as these diseases have extremely diverse management.

Thyroid Cytology in India: Contemporary Review and Meta-analysis

Fine-needle aspiration cytology (FNAC) is a screening test for triaging thyroid nodules, aiding in subsequent clinical management. However, the advantages have been overshadowed by the multiplicity of reporting systems and a wide range of nomenclature used. The Bethesda System for Reporting Thyroid Cytopathology (TBSRTC) was formulated in 2007, to give the world a uniform thyroid cytology reporting system, facilitating easy interpretation by the clinicians. Here, we review the status of thyroid FNAC in India in terms of various reporting systems used including a meta-analysis of the previously published data. An extensive literature search was performed using internet search engines. The reports with detailed classification system used in thyroid cytology were included. The meta-analysis of published data was compared with the implied risk of malignancy by TBSRTC. More than 50 studies were retrieved and evaluated. TBSRTC is currently the most widely used reporting system with different studies showing good efficacy and interobserver concordance. Ancillary techniques have, as of now, limited applicability and acceptability in thyroid cytology in India. Twenty-eight published articles met the criteria for inclusion in the meta-analysis. When compared with TBSRTC recommendations, the meta-analysis showed a higher risk of malignancy for categories I and III. Thyroid FNAC is practiced all over India. TBSRTC has found widespread acceptance, with most institutions using this system for routine thyroid cytology reporting. However, reasons for a high malignancy risk for categories I and III need to be looked into. Various possible contributing factors are discussed in the review.