ADRENAL CORTICAL ADENOMA

CLINICAL FEATURES

• Typically unilateral, solitary, benign;

• Endocrine abnormality: primary hyperaldosteronism > Cushing's syndrome > virilization and occasional feminization;

• Image studies: well-defined, smooth contour, and homogeneous.

GROSS FINDINGS

• Solitary, unilateral and unicentric;

• Often < 50 grams;

• Sharply circumscribed or encapsulated;

• Cut surface: homogeneously yellow or golden-yellow, or with foci of dark discoloration (hemorrhage or lipid depletion);

• Black adenoma: diffusely dark brown.

MICROSCOPIC FINDINGS

• Often have relatively smooth pushing border without a well-defined fibrous capsule;

• Usually have broad fields of pale-staining, lipid-rich cells with relatively uniform nuclei and clear cytoplasm;

• Architectures: nests, alveolar, short cord, narrow interconnecting trabeculae, or a mixture of these patterns;

• Cytology: compared with the normal cortical cells, the tumor cells are usually larger with different quality of cytoplasm and variation in nuclear size and configuration; tumor cells have abundant pale-staining, lipid-rich cytoplasm and relatively distinct cell borders; lipid-depleted or poor cells have eosinophilic cytoplasm and sometimes conspicuous lipochrome pigment;

• Tumor cell nuclei are usually single and round to oval, vesicular; may have moderate nuclear enlargement and hyperchromasia;

• Rare mitotic figures;

• Other features: occasional foci of diversity of cytological features, balloon cells, or spindle cells; lipomatous, myelipomatous or bony metaplasia;

• Adrenal remnant may show cortical atrophy in association with Cushing's syndrome.

SUBTYPES

• Black (pigmented) adenoma: similar architectures but composed of predominantly tumor cells with compact, eosinophilic cytoplasm and variable amounts of brown or golden brown cytoplasmic pigments;

• Cortical adenoma with Conn's syndrome: usually smaller than with Cushing's syndrome, hyperplasia of Zona Glomerulosa, spironolactone bodies (in zona glomerulosa, small, 2-12 um,  round to oval intracytoplasmic inclusions, lightly eosinophilic, with a laminated, scroll-like appearance, often demarcated from surrounding cytoplasm by a small clear halo);

• Oncocytic adrenal cortical adenoma: abundant mitochondria.

DIFFERENTIAL DIAGNOSES

• Adrenal cortical carcinoma: larger (>100 grams), more atypia, necrosis and mitoses,

ELECTRON MICROSCOPIC FINDINGS

• Abundant cytoplasmic lipid droplets in variable sizes and densities from cell to cell.

REFERENCES

• AFIP, tumor of the adrenal glands and extra-adrenal paraganglia, series 3;