Anaplastic thyroid carcinoma with postpartum progression to stage IVC disease in a 23-year-old pregnant woman: a rare presentation with diagnostic challenges and treatment barriers leading to poor disease control and fatal outcome—a case report

Abstract Background Anaplastic thyroid carcinoma is a rare and aggressive malignancy, with a poor prognosis and is infrequently encountered in young individuals, particularly pregnant women. This case highlights the diagnostic and therapeutic challenges posed by this aggressive cancer when it occurs during pregnancy, a situation that demands a multidisciplinary approach balancing maternal and fetal well-being. The atypical presentation in a young, pregnant patient warrants reporting due to its rarity and the complexities involved in management. Case presentation A 23-year-old pregnant Pashtun female in her second trimester presented with a rapidly enlarging neck mass, dysphagia, dyspnea, and unintentional weight loss. Initial investigations, including thyroid function tests, were within normal limits. Importantly, normal thyroid function tests do not exclude thyroid malignancy and should not delay further evaluation when clinical findings are suspicious. Thyroid ultrasonography and fine-needle aspiration cytology (FNAC) were not performed at initial presentation due to resource constraints and the clinical priority of securing the airway. A tracheostomy was performed to manage airway obstruction, and biopsy findings, supported by a partial immunohistochemical panel, were consistent with anaplastic thyroid carcinoma. Given the pregnancy and significant ethical and logistical barriers, immediate aggressive treatment including surgery, radiotherapy, and systemic therapy was deferred following multidisciplinary discussion. Following an uncomplicated delivery, the patient's condition deteriorated, with tumor progression and systemic metastasis; postpartum imaging revealed a large neck mass encasing the carotid artery and hepatic lesions radiologically consistent with metastases (without histologic confirmation), on the basis of which American Joint Committee on Cancer (AJCC) Stage IVC disease was assigned. Despite supportive care, the patient succumbed to the disease due to its aggressive nature and systemic involvement. Conclusions This case underscores the difficulties in diagnosing and managing anaplastic thyroid carcinoma in young, pregnant women. The normal thyroid function tests and the presence of pregnancy can mask or delay the diagnosis, leading to rapid disease progression. A heightened awareness and a multidisciplinary approach are essential for early recognition and tailored management strategies to optimize outcomes for both the mother and the fetus, though the prognosis remains guarded in advanced stages. This case emphasizes the need for further research to establish clear guidelines for the management of thyroid malignancies during pregnancy.