Adrenocortical Adenoma

Epidemiology and Etiology:

•  >1cm adenomas found in autopsy series – 1.5-7.0%
• incidentalomas are common with CT / MRI – up to 4%
• uncommon < 30y
• increase in frequency with age
• M=F
• Sex hormone secreting are rare

Common sites:

Gross features:

• yellow to yellow-brown
• mineralocorticoid adenoma (Conn’s) is bright golden yellow
• < 100g (vast majority)
• Unilaterateral (majority)
• functional adenomas show atrophy of adjacent cortex
• EXCEPT mineralocorticoid adenoma (Conn’s) because aldosterone is ACTH independent
• Pigmented “black” adenoma (variant)
• hemorrhage and necrosis are rare
• Cannot reliably distinguish grossly between various hormone secreting or non-functioning
• Adjacent gland atrophic if functioning
• Paradoxical hyperplasia of zona glomerulosa in aldosterone secreting

Histologic features:

• cells similar to normal adrenal cortex
• eosinophilic to vacuolated cytoplasm
• nuclei usually small
• some pleomorphism may be present
• low mitotic activity
• can’t definitively distinguish between various hormone secreting and non-functioning

• Adjacent gland atrophic if functioning
• Paradoxical hyperplasia of zona glomerulosa in aldosterone secreting

• Mineralocorticoid-secreting (Conn’s syndrome):
• Clear-cell adenoma
• Spironolactone bodies
• Pigmented “black” adenoma:
• Intracytoplasmic lipofuscin
• Oncocytic adrenal cortical adenoma:
• Abundant eosinophilic cytoplasm (finely granular)
• Non-functional
• Myxoid variant:
• Abundant extracellular mucin
• May show pseudoacinar formation

Immunophenotype:

Marker:	Sensitivity:	Specificity:
Inhibin
MART-1
Steroidogenic factor 1 (SF-1)

Molecular features:

• Most are sporadic 
• hereditary syndromes:
• Li-Fraumeni syndrome
• Beckwith-Wiedemann syndrome
• Carney complex

Other features:

•  non-functioning in >85%
• non-functioning and < 5cm – likely benign
• larger may be malignant
• functioning
• hyperaldosteronism most frequent
• Cushing syndrome next
• Virilization next
• Feminization (rare)
• Pigmented “black” adenoma:
• No clinical significance
• Benign
• May be associated with Cushing syndrome

• Oncocytic adrenal cortical adenoma:

• Usually non-functioning

References:

• Robbins 2005

• WHO Tumours of Endocrine Organs (2004)