Occult Metastatic Carcinoma in Pregnancy: Diagnostic Challenges of Cancer of Unknown Primary Origin with Disseminated Vertebral Involvement

Abstract

Malignancy during pregnancy is uncommon and can be difficult to recognise because disease-related symptoms may overlap with physiological changes of gestation. Cancer of unknown primary (CUP) presenting with disseminated skeletal involvement during pregnancy is particularly rare. This report describes a 36-year-old gravida 3 para 2 woman who presented at 33 weeks’ gestation with progressive bilateral hip pain, lower-limb weakness, impaired mobility, and functional decline. Magnetic resonance imaging demonstrated extensive axial and appendicular skeletal lesions. Breast, neck, hepatobiliary, and renal tract ultrasonography did not identify a primary malignancy. Serum alpha-fetoprotein was elevated, whereas the other assessed tumour markers were unremarkable. Because neurological symptoms and mobility continued to worsen, multidisciplinary planning led to elective caesarean delivery with bilateral tubal ligation at 35 weeks and 6 days after antenatal corticosteroid administration. Initial iliac crest biopsies were inconclusive. Repeat sampling from coeliac lymph nodes confirmed metastatic epithelial carcinoma, while immunohistochemical findings remained non-specific for the primary site. Postpartum computed tomography demonstrated an enlarging hepatic mass and worsening abdominal lymphadenopathy, but the pattern was not characteristic of hepatocellular carcinoma. The patient completed palliative pelvic radiotherapy, and systemic chemotherapy was planned but not undertaken. This case illustrates the diagnostic difficulty of CUP in pregnancy and the importance of timely imaging, repeat tissue sampling, and coordinated multidisciplinary management when progressive musculoskeletal symptoms are accompanied by neurological or functional impairment.