CASE REPORT Thymus hyperplasia after resolution of hypercortisolism in ACTH-dependent Cushing’s syndrome: the importance of thymic vein catheterization Malebranche Berardo C Cunha Neto, Ma ´rcio Carlos Machado, Fla ´via Mesquita, Nina Rosa de Castro Musolino, Andrea Cecı ´lia Toscanini, Gilberto Ochman, Valter Angelo S Cescato, Raul Marino Jr and Manoel Jacobsen Teixeira Neuroendocrine Unit, Division of Neurosurgery, Hospital das Clı ´nicas, University of Sao Paulo School of Medicine, Rua Ovı ´dio Pires de Campos # 785, Cerqueira Cesar, 01060-970, Sao Paulo, SP, Brazil (Correspondence should be addressed to M B C Cunha Neto; Email: malebrancheb@uol.com.br) Abstract Thymic hyperplasia has been described after the resolution of hypercortisolism from several etiologies, causing great diagnostic dilemmas. We describe a case where the catheterization of the thymic vein was essential for the differential diagnosis of a thymic enlargement in an adrenalectomized patient with ACTH-dependent Cushing’s syndrome. The patient was a 48-year-old female with clinical and laboratorial data suggesting Cushing’s disease. She underwent a transsphenoidal surgery with no tumor visualization and no remission of the syndrome. Histopathological studies disclosed a normal pituitary. She underwent a bilateral adrenalectomy and 8 months later a chest CTshowed an increase of left thymic lobe, which was previously non-existent. After a negative 111 In-pentetreotide scintigraphy, the patient underwent simultaneous and bilateral catheterism of the petrosus sinuses and catheterization of the thymic and inominate veins and no ACTH gradient was shown among the sites of collection. She did not undergo thoracotomy and a follow-up was established. During the evolution, there was a spontaneous regression of the thymic lesion 38 months after the diagnosis. The ACTH gradient during the catheterization of thymic vein was essential for the differential diagnosis of the thymic enlargement tumor after hypercortisolism resolution in ACTH-dependent Cushing’s syndrome, especially in this case, where the ACTH source was occult, thus avoiding an invasive surgical procedure for a benign entity with spontaneous resolution. European Journal of Endocrinology 154 807–811 Introduction Corticotropic tumors represent 60–70% of all cases of endogenous hypercortisolism, and ectopic adreno- corticotropin (ACTH) secretion accounts for 10–20% of ACTH-dependent Cushing’s syndrome (1–3). Most of these ectopic tumors are located in the thoracic region (bronchial carcinoid tumor and small-cell lung carci- noma) (1, 4). Thymic images are important for the differential diagnosis of ACTH-dependent Cushing’s syndrome, since thymic tumors can represent the source of ACTH production. In a large series (nZ530) of ectopic tumors, thymic etiologies (carcinoid tumors, malignant thy- moma and thymus hyperplasia) accounted for 11.2% of the cases (4). Thymic hyperplasia has been described after the resolution of hypercortisolism in Cushing’s syndrome, more commonly after adrenalectomy, but also after the resection of bronchial carcinoid tumors and corticotropic adenomas and following mitotane, ketoconazole and RU-486 use (5–7). The appearance of a thymic mass in a bilaterally adrenalectomized patient with ACTH-dependent Cushing’s syndrome can create a dilemma regarding the differential diagnosis between thymic hyperplasia and ectopic tumor, especially in cases where the source of ACTH production remains occult. We report a patient with post-adrenalectomy thymic enlargement who underwent simultaneous and bilat- eral catheterism of the petrosus sinuses and - catheterization of the thymic and inominate veins in whom the absence of ACTH gradient among the sites and periphery was important in conveying the benign nature of the thymic enlargement and preventing the surgical investigation of the lesion. q 2006 Society of the European Journal of Endocrinology DOI: 10.1530/eje.1.02154 Online version via www.eje-online.org European Journal of Endocrinology (2006) 154 807–811 ISSN 0804-4643 Downloaded from Bioscientifica.com at 06/05/2020 10:24:42PM via free access