CORTICOMEDULLARY TUMOR OF THE LEFT ADRENAL GLAND WITH ELEMENTS OF PHEOCHROMOCYTOMA AND ADRENOCORTICAL ADENOMA
Corticomedullary tumor (CMT) of the adrenal gland is extremely rare. Only a few cases have been reported in the literature consisting of nests and cords of pheochromocytoma and cortical adenoma growing within the same tumor mass (1).
Microscopically, CMT is characterized by a mixture of medullary pheochromocytoma cells with adrenocortical tumor cells (IMAGE 01) creating a composite tumor having both cortical and medullary characteristics. Pheochromocytoma cells have round-oval nuclei with coarsely clumped chromatin and abundant finely eosinophilic granular cytoplasm (IMAGE 02). Cortical adenoma cells have clear cytoplasm (IMAGE 03). There is evidence of thrombosis and recanalization of vascular channels within the adrenal tumor (IMAGES 04 and 05).
Immunohistochemical stains for chromogranin (IMAGE 06), synaptophysin (IMAGE 07) and neuron specific enolase (IMAGE 08) are positive for the pheochromocytoma cells, and negative for the cortical adenoma cells. S-100 protein expression shows that the sustentacular cells are focally present at the peripheries of the tumor cell clusters (IMAGE 09), which supports the diagnosis of pheochromocytoma. In addition, review of the literature demonstrates that the pheochromocytoma and cortical adenoma components of CMT are easily distinguished by the antibody to the mitochondrial antigen 113-1. All cortical adenoma cells showed strong and diffuse reactivity for this antibody, while pheochromocytoma cells only showed very weak reactivity (1).
Ultrastructural examination based on formalin fixed paraffin embedded tissue demonstrates membrane bound neuroendocrine granules in which catecholamines are stored, and smooth endoplasmic reticulin in the tumor cells (IMAGES 10 and 11), which supports the diagnosis of CMT.
Rare cases of pheochromocytoma can arise in association with cortical adenoma. These cortical adenomas occur either as a separate tumor, or as a component of CMT consisting of both cortical adenoma cells and pheochromocytoma cells. Clinically, these patients suffer from Cushing's syndrome and paroxysmal hypertension. However, the patient in our case presented with only atypical hypertension, and her stimulated cortisol and aldosterone levels were within normal limits, which demonstrated that the component of cortical adenoma of the CMT was nonfunctioning.
The histogenesis of CMT is not well-defined. The question of whether the cortical adenoma and pheochromocytoma components of CMT grow independently, or their growth is interrelated is difficult to resolve. Pheochromocytoma can rarely produce ACTH and a possibility exists that this ectopic ACTH production might initiate the cortical adenoma component of this tumor. The extreme rarity of the published cases of CMTs suggests that CMT might represent one of the "collision" tumors.
Contributed by Yan Peng MD, PhD and Sydney Finkelstein, MD