Background: Several cases of hypernatremic dehydration complicated by consumption coagulopathy and peripheral gangrene have been reported.
Case report: A 4.5 month-old boy was admitted suffering from acute gastroenteritis with cyanotic edema of the distal part of the left leg and foot. His serum sodium was 160 mEq/l, potassium 5.8 mEq/l and urea 27.6 mMol/l. His prothrombin level was 44%, fibrinogen 0.65 g/l and the number of platelets was 20,000/mm3. Blood cultures were negative. Ultrasonography showed a subperiostal effusion in the posterolateral part of the left tibia with edema of the adjacent soft tissues. Culture of the fluid was negative. The patient was rehydrated. Several phlyctenes appeared on the left foot; cultures of the exudate remained sterile. His condition gradually normalized within two weeks and ultrasonography performed at the 15th day was normal.
Conclusion: The subperiostal effusion seen in our patient could have been due to microthrombosis of the metaphyseal vessels, following severe dehydration.