Coexistence of Severe Valvular Pulmonary Stenosis and Papillary Thyroid Carcinoma: A Rare Association or Coincidence?

Papillary thyroid carcinoma (PTC) is the most common thyroid malignancy. Pulmonary valve stenosis (PVS), on the other hand, is a congenital valvular heart disease characterized by narrowing of the right ventricular outflow tract, which can lead to right-sided heart failure if severe. To date, there are no reported cases in the literature describing a co-occurrence of PTC and PVS in the same individual. Our patient was a 28-year-old male, a smoker with a five-pack-year history, who presented with a painless right neck swelling of five months duration. Physical examination revealed a firm, non-tender right cervical lymphadenopathy. Thyroid examination showed that the trachea was midline, thyroid was non-palpable, without tenderness, nodules, or bruit, and no signs of exophthalmos or proximal muscle weakness. Heart examination revealed a thrill, a normal first and second heart sounds, and a systolic crescendo-decrescendo murmur heard at the left upper sternal border. Jugular venous pressure (JVP) was not elevated. No signs of ascites, hepatomegaly, or lower limbs edema. The patient had no syndromic features. Laboratory wise was unremarkable. In regard to imaging, neck ultrasound showed multiple enlarged heterogeneous rounded structures in the right cervical region, the largest measures 2.9 x 2.5 cm. The visualized parts of the thyroid gland appeared unremarkable. Computed tomography (CT) of the brain, chest, abdomen, and pelvis was unremarkable apart from cardiomegaly in the CT chest. Further assessment by echocardiography showed severe valvular pulmonary stenosis. An ultrasound-guided fine needle aspiration of the right cervical lymph node showed papillary thyroid carcinoma. A thorough literature review using PubMed revealed no documented cases of concurrent PTC and PVS, supporting the novelty of this case. While the possibility of a coincidental coexistence cannot be excluded, this unique case raises the possibility of a shared developmental or molecular pathway-such as dysregulation of the rat sarcoma (RAS)/mitogen-activated protein kinase (MAPK) signaling cascade-linking both conditions. While a coincidental occurrence remains plausible, the overlap with pathways implicated in RASopathies warrants further investigation. Multidisciplinary evaluation was critical in planning appropriate oncologic and cardiologic management. This case underscores a rare coexistence of papillary thyroid carcinoma and severe pulmonary valve stenosis in a young adult without any identifiable congenital syndrome. Although the association may be incidental, it prompts consideration of potential shared developmental or molecular mechanisms. Importantly, the presence of severe pulmonary stenosis has significant clinical implications, contributing to symptom burden and influencing the timing and selection of therapeutic interventions, including both cardiac and oncologic management strategies.