Cyclic ACTH-secreting thymic carcinoid: a case report and review of the literature

Abstract

Cyclic Cushing's syndrome (CS) due to thymic carcinoid is a rare disorder. We report a case of cyclic CS due to ectopic adrenocorticotropic hormone (ACTH)-secreting atypical thymic carcinoid tumor and reviewed similar cases published in the literature. Our patient had hypercortisolemia lasting approximately one month, followed by normal cortisol secretion, with relapse one year later. Histopathology revealed an atypical ACTH-positive thymic carcinoid. Ectopic CS can be derived from atypical thymic carcinoids, which can be aggressive tumors with early relapse, suggesting that this type of tumor probably needs aggressive treatment.

Figure 1. Chest computed tomography scan in the coronal ( A ), sagittal ( B ) and axial ( C ) views showing a 2.0×1.1×1.4 cm tumor in the anterior mediastinum (arrows) and ⁶⁸Ga-DOTATOC-PET CT scan in the axial view (D) exhibiting focal radiotracer uptake in the anterior mediastinum (SUVmax = 6.7/15×11 mm).

Figure 2. Surgical specimen with the tumor (*) measuring 1.5 cm with the thymic remnant showing several carcinoid tumorlets in the surrounding abundant fat.

Figure 3. Histopathology of atypical thymic carcinoid. ( A ) Hematoxylin-eosin staining, ×200, showing a solid and trabecular growth pattern among a delicate vascularized fibroconjunctival stroma; ( B ) Immunohistochemistry, ×200, showing granular membranous ACTH staining; ( C ) Immunohistochemistry, ×200, showing strong membranous chromogranin A staining; ( D ) Immunohistochemistry, ×200, showing a high Ki67 proliferation index.