Endocrine Abstracts

Introduction: Dermatomyositis is an inflammatory connective-tissue disease, characterized by inflammation of the muscles and the skin. It is more frequent among women and in 25% of cases it is related to malignancy, such as ovarian, breast, colon cancer, melanoma, non-Hodgkin’s lymphomas, lung cancer, myelo-hyperplastic syndromes, and nasopharyngeal cancer. In 1/3 of cases dermatomyositis precedes malignancy, in 1/3 they present simultaneously, and in the remaining 1/3 of cases it occurs after the diagnosis of malignancy.

A common paraneoplastic syndrome caused by ectopic hormone production is hyponatremia, which occurs in 15% of SCLC patients. Patients frequently but not always experience a decline in sodium level at relapse, making declining sodium a tumor marker for cancer progression, although this has not been prospectively studied. Small studies have suggested that hyponatremia is associated with shortened survival and it is poor prognostic factor for patients with SCLC.

Case report: A 67-year-old woman admitted to our hospital on August 23rd, 2019, due to severe hyponatremia. The patient was diagnosed with Dermatomyositis one month earlier, according to the results of the following physical, laboratory, EMNG examinations and biopsies. For the last 2 years, the patient was referred to the pulmologist due to productive cough, chest tightness and shortness of breath. A CT scan of the chest was performed in Mart 2019, which showed no significant changes.

Clinical findings on admission

Punctuate red rashes scattering on the face, chest and extremities, difficulty swallowing, proximal muscular weakness were noted. Pulse oxygen saturation (SPO₂) was 85%, BP 100/60 mmHg without orthostasis, pulse 86/min. She had no edema or ascites. Laboratory findings: TSH 1.45 mIU/l, cortisol 546 nmol/l, blood urea 4,0 mmol/l, creatinine 38 mcmol/l, CK 1194 IU/l, AST 123 IU/l, ALT 46 IU/l, LDH 389 IU/l, plasma sodium (P_Na) 116 mmol/l, potassium 3.9 mmol/l, serum osmolality 239 mOsm/kg/H2O, uric acid 94 mcmol/l, urine osmolality 557 mOsm/kg H2O, urine sodium (U_Na) 106 mmol/l. MSCT examination of the chest revealed a large tumor mass in the upper mediastinum 118 × 56 mm with numerous macronodular focal changes in the lung. Biopsy from mediastinal lymph nodes was performed and histopatological findings showed: Small cell carcinoma. The immunohistochemistry assay of lymph node: CK ±, Synaptophysin +, CD56 +, LCA-, Ki67 positive in 90% of tumor cells.

Numerous secondary deposits have been identified in the brain by NMR examination.

She died on 12th of September, 2019, 20 days after being diagnosed with hyponatremia.