Papillary Thyroid Carcinoma (PTC) accounts for approximately 85% of thyroid malignancies and is characterized by an excellent long-term prognosis despite its marked tendency for lymphatic spread. Cervical lymph node metastases are present in 20–50% of patients at initial diagnosis and may be even more frequent when occult microscopic metastases are systematically investigated. Although lymph node involvement has limited influence on disease-specific survival in young patients, it increases the risk of locoregional recurrence and influences postoperative management, including consideration of radioactive iodine ablation and long-term surveillance [19–22].

Tuberculous lymphadenitis is the most frequent manifestation of extrapulmonary tuberculosis. Cervical lymph nodes are commonly involved in peripheral tuberculous lymphadenitis. Despite declining tuberculosis incidence in many developed countries, the disease remains an important consideration in North Africa, including Morocco, where cervical tuberculosis should be included in the differential diagnosis of chronic cervical lymphadenopathy [22–25].

Although both diseases frequently involve the cervical lymphatic chains, their coexistence remains uncommon. Since the first descriptions of thyroid carcinoma associated with tuberculous lymphadenitis, only isolated case reports and small case series have been published. Most reported patients had metastatic cervical lymph nodes and tuberculous lymphadenitis simultaneously but in different lymph nodes. Histologically proven coexistence of metastatic PTC and tuberculous granulomatous inflammation within the same lymph node has been reported only exceptionally, making our observation particularly noteworthy [23,26–30,42].

Our patient exhibited three pathological patterns within the same neck-dissection specimen. Among the 13 dissected lymph nodes, seven contained metastatic papillary thyroid carcinoma and six demonstrated isolated tuberculous lymphadenitis. Most importantly, three of the metastatic lymph nodes simultaneously harbored metastatic papillary carcinoma and caseating tuberculous granulomas. This complex pathological distribution emphasizes that cervical lymphadenopathy associated with thyroid carcinoma cannot always be attributed to a single pathological process. Only a limited number of similar observations have been described in the literature.

The pathophysiological mechanisms underlying this coexistence remain uncertain. The most straightforward explanation is coincidence, particularly in tuberculosis-endemic countries where latent Mycobacterium tuberculosis infection is common. Other hypotheses suggest that chronic granulomatous inflammation may contribute to carcinogenesis through prolonged cytokine production, oxidative stress, angiogenesis, and DNA damage, whereas malignancy-associated alterations in cellular immunity may facilitate reactivation of dormant tuberculosis within regional lymph nodes. However, these mechanisms remain speculative because of the rarity of reported cases [31–34].

The diagnostic challenge arises primarily from the substantial overlap between metastatic papillary thyroid carcinoma and tuberculous lymphadenitis. Clinically, both conditions may present as slowly enlarging, painless cervical masses. Constitutional symptoms such as fever, night sweats, weight loss, and chronic cough may be absent in isolated cervical tuberculosis, while papillary thyroid carcinoma may remain asymptomatic even in the presence of nodal metastases. Our patient presented only with painless left cervical swelling and no systemic manifestations, illustrating the limited discriminatory value of clinical findings alone [22,24,27].

Radiological assessment also has important limitations. Ultrasonography remains the imaging modality of choice for evaluating thyroid nodules and cervical lymph nodes. Rounded morphology, loss of the fatty hilum, microcalcifications, cystic degeneration, heterogeneous echotexture, and peripheral vascularity may suggest metastatic papillary thyroid carcinoma. However, tuberculous lymphadenitis can show overlapping features because of caseous necrosis, fibrosis, and dystrophic calcification. Consequently, imaging alone may not reliably distinguish these two entities [24,28,35,36].

Fine-needle aspiration cytology remains central to preoperative assessment, but its diagnostic performance may be limited when tuberculosis and metastatic carcinoma coexist. Aspiration of a granulomatous area may fail to identify malignant epithelial cells, whereas aspiration of metastatic tissue may overlook adjacent tuberculous inflammation. Combining cytology with appropriate microbiological or immunological investigations may improve the preoperative diagnosis of cervical tuberculous lymphadenitis associated with papillary thyroid carcinoma [27,37]. In the present case, FNAC was performed only on the thyroid nodule and yielded Bethesda category V, whereas the nature of the cervical lymphadenopathy was established intraoperatively.

One of the most striking aspects of this case was the intraoperative discovery of abundant caseous material, which immediately raised suspicion for tuberculosis and was supported by frozen-section examination. Simultaneously, frozen-section analysis of the thyroid specimen confirmed papillary thyroid carcinoma, allowing the surgical strategy to be adapted during the same procedure. This finding illustrates the value of intraoperative pathological assessment when unexpected lesions are encountered.

Histopathological examination remains the diagnostic gold standard. Classical papillary thyroid carcinoma is characterized by papillary architecture and typical nuclear features, whereas tuberculous lymphadenitis demonstrates epithelioid granulomas, Langhans-type giant cells, and central caseous necrosis. Demonstration of both processes within the same lymph node establishes true histopathological coexistence rather than simultaneous involvement of separate nodes. In our patient, three lymph nodes exhibited both metastatic carcinoma and caseating granulomatous inflammation, providing pathological confirmation of this rare association.

An important differential diagnosis is a sarcoid-like granulomatous reaction, which may occur in lymph nodes draining malignant tumors. Unlike tuberculous lymphadenitis, sarcoid-like reactions typically lack central caseous necrosis [39,40]. In the present case, the abundant intraoperative caseous material and the histological demonstration of caseating granulomas strongly supported tuberculous lymphadenitis rather than a non-infectious granulomatous reaction.

Management should address both diseases while respecting oncological principles. Clinically evident lateral cervical lymph node metastases from papillary thyroid carcinoma require therapeutic compartment-oriented neck dissection, while postoperative radioactive iodine is considered according to recurrence-risk stratification. Tuberculosis should be treated with standard multidrug antituberculous therapy without unnecessary delay of oncological treatment [19,20,38]. In our patient, total thyroidectomy with therapeutic left lateral neck dissection was followed by radioactive iodine ablation, while histologically confirmed tuberculous lymphadenitis was treated concomitantly with standard antituberculous therapy. The subsequent course was favorable, with no evidence of recurrence during follow-up.

Hachicha et al. recently reported a similar patient with metastatic papillary thyroid carcinoma associated with cervical tuberculous lymphadenitis who underwent total thyroidectomy, neck dissection, radioactive iodine ablation, and antituberculous therapy, with no recurrence after two years of follow-up. The present case is distinguished by the histological demonstration of both metastatic carcinoma and tuberculous granulomatous inflammation within the same lymph nodes [41].

The principal strength of this report is the detailed pathological assessment of the neck-dissection specimen, which identified metastatic nodes, isolated tuberculous nodes, and mixed nodes containing both processes. This pattern illustrates the complexity of interpreting cervical lymphadenopathy in patients with thyroid carcinoma in tuberculosis-endemic settings. The principal limitation is the single-patient nature of the report, which precludes conclusions regarding the frequency or biological relationship of these two diseases.

This case highlights the importance of considering concomitant tuberculosis in patients with papillary thyroid carcinoma and extensive cervical lymphadenopathy. Neither imaging nor cytology alone can reliably distinguish metastatic disease from tuberculous lymphadenitis when both conditions coexist. Careful intraoperative assessment and meticulous histopathological examination are essential to establish the diagnosis and guide multidisciplinary management. The demonstration of metastatic papillary thyroid carcinoma and tuberculous granulomatous inflammation within the same cervical lymph nodes adds to the limited literature on this unusual clinicopathological association.