Table 1.

HISTALDO consensus for nomenclature and histopathology of adrenal cortical lesions in unilateral primary aldosteronism

Histopathological entity	Abbreviation	Definition
Aldosterone-producing adrenocortical carcinoma	APACC	Aldosterone-producing malignant neoplasms, including variants, follow the same pathologic criteria of other adrenocortical cancers.
Aldosterone-producing adenoma	APA	Well circumscribed CYP11B2a-positive solitary neoplasm (≥ 10 mm diameter) composed of clear or compact eosinophilic cells or both cell types.
Aldosterone-producing nodule	APN	CYP11B2-positive lesion (<10 mm diameter)b morphologically visible with hematoxylin-eosin staining. An APN often displays a gradient of CYP11B2 immunostaining decreasing in intensity from the outer to the inner part of the lesion.
Aldosterone-producing micronodule (formally known as aldosterone-producing cell cluster)	APM	CYP11B2-positive lesion (<10 mm diameter)b composed of zona glomerulosa cells located beneath adrenal capsule that do not differ in morphology from adjacent adrenocortical cells by hematoxylin-eosin staining. An APM often displays a gradient of CYP11B2 immunostaining decreasing in intensity from the outer to the inner part of the lesion.
Multiple aldosterone-producing nodules or multiple aldosterone-producing micronodules (formally known as micronodular hyperplasia)	MAPN or MAPM	Multiple APN or multiple APM located beneath the adrenal capsule with intermittent regions of normal zona glomerulosa. MAPN and MAPM can coexist in the same adrenal.
Aldosterone-producing diffuse hyperplasia	APDH	Relatively broad and uninterrupted strip of zona glomerulosa cells with more than half of these cells displaying CYP11B2-positive immunostaining.

^aCYP11B2 = aldosterone synthase. CYP11B2 immunostaining must be performed using a well validated antibody (10).

^bThe histopathologic diagnosis of small lesions requires appropriate tissue sectioning to allow assessment of greatest diameter or dimension and to avoid distortion of lesion architecture.