RESUMO
We report a case of Cushing disease whose microadenoma was not identified by MRI with dynamic study and whose sphenoid sinus was conchal in type. Venous sampling test in the bilateral inferior petrosal sinus demonstrated ACTH hypersecretion on the right side. The patient underwent transsphenoidal surgery. A poorly pneumatized sphenoid sinus was drilled effectively, guided by the STEALTH navigation system. After the first operation, the patient's serum ACTH concentration was still high, suggesting that tumor removal was incomplete. Then she underwent the second operation and the residual tumor was completely removed with the assistance of the STEALTH navigation system again. Postoperatively, her serum ACTH concentration dropped below 5 pg/ml. In this case, inferior petrosal sinus sampling was extremely helpful for the diagnosis of Cushing disease, and operations were able to be performed safely using the neuronavigation system in drilling of the incompletely pneumatized sphenoid sinus.
