Small cell carcinoma of the cervix complicated by syndrome of inappropriate antidiuretic hormone secretion: a case report

Abstract

Small cell carcinoma of the cervix is a rare malignant tumor in the clinical setting. Clinical manifestations of this tumor are mostly similar to those of normal types of cervical cancer. Small cell carcinoma of the cervix only shows symptoms of neuroendocrine tumors, such as syndrome of inappropriate antidiuretic hormone secretion (SIADH). Most of the hyponatremia caused by SIADH can be managed after removal of the cause. Hyponatremia is a predictor of poor prognosis and can be used as an indicator of partial recurrence. We report a case of small cell carcinoma of the cervix complicated by SIADH. Our patient presented with irregular vaginal bleeding after menopause. After one cycle of chemotherapy, there was trembling of the limbs, and a laboratory examination showed low Na⁺ and low Cl^- levels. After limited water intake, intravenous hypertonic saline, and intermittent diuretic treatment, the patient's blood Na⁺ levels returned to normal. After a radical operation, the above-mentioned symptoms disappeared.

Keywords: Small cell carcinoma of the cervix; chemotherapy; electrolyte; hyponatremia; neuroendocrine tumor; syndrome of inappropriate antidiuretic hormone secretion.

Figure 1.

Contrast-enhanced computed tomography of the pelvis (a). The arrow indicates a cervical lesion, which is approximately 4.8 × 5.7 × 6.2 cm³ in size. The lesion shows uneven enhancement, and an unclear boundary between the local cervix and posterior wall of the bladder. Dissected specimen postoperatively (b). Cervical swelling of approximately 5 cm in diameter can be seen. Additionally, there was a hard endogenous mass in the cervical canal, which was located in the posterior wall of the cervix, and an enlarged lymph node with a diameter of approximately 1 cm in the right inguinal region. Image showing pathology under a light microscope (c) (hematoxylin and eosin, × 100). Cervical cancer cells and tumor thrombus were found in the vasculature.