Adrenocortical carcinoma (ACC) is a rare but extremely aggressive malignant tumor originating from the adrenal cortex. Its incidence is 1-2/million/year. It is usually large at diagnosis (>6 cm, mean 10-12 cm). 60% of cases are functional, excessively secreting cortisol (most common), androgen, estrogen, or aldosterone — may present with virilization, Cushing syndrome, or feminization. More common in children (65% functional) and associated with Li-Fraumeni syndrome (TP53 mutation). Prognosis is poor — 5-year survival is 60-80% in stage I-II, 40-50% in stage III, and <15% in stage IV. On CT, appears as a large, heterogeneous, irregularly marginated mass; necrosis, hemorrhage, calcification, and local invasion (renal vein, IVC, kidney, diaphragm) are common.
Age Range
30-70
Peak Age
50
Gender
Female predominant
Prevalence
Rare
ACC results from malignant transformation of adrenal cortex cells. At the molecular level, the most common findings are IGF-2 (insulin-like growth factor 2) overexpression (90%), Wnt/β-catenin signaling pathway activation, TP53 mutation (25-30%, Li-Fraumeni), and 11p15 locus LOH (loss of heterozygosity). The large tumor size reflects rapid proliferation and invasive growth potential. In functional ACC, malignant cells continue to express steroidogenesis enzymes but produce hormones irregularly and uncontrolled. The pathophysiological basis of imaging findings: heterogeneous appearance on CT reflects areas of necrosis (inadequate blood flow — rapidly growing tumor outpaces vascular supply), hemorrhage (fragile neovascular vessels), and calcification (dystrophic calcification — necrotic tissue mineralization) within the tumor. Irregular margins reflect invasive growth into surrounding tissues. Slow washout results from contrast remaining longer in tumor interstitium due to irregular tumor neovascularization and increased vascular permeability.
An adrenal mass >6 cm in size, heterogeneous (necrosis + hemorrhage + calcification), with irregular margins, avid heterogeneous enhancement, and local invasion signs (IVC tumor thrombus, renal vein invasion, adjacent organ invasion) is highly suspicious for ACC. Size alone is the strongest malignancy indicator — ACC risk is 25% in lesions >4 cm and >85% in >6 cm.
On non-contrast CT, ACC appears as a large (usually >6 cm), heterogeneous, soft tissue density (>20 HU) mass. Internally, low-attenuation necrosis areas, high-attenuation hemorrhagic foci, and calcifications (30%) may be seen. Irregular or lobulated margins are typical. Invasion signs: renal vein or IVC tumor thrombus, direct invasion of adjacent organs, retroperitoneal lymphadenopathy.
Report Sentence
A heterogeneous, irregularly marginated mass measuring approximately ___ cm in the left/right adrenal gland is seen, containing areas of necrosis and calcification; size and morphology are consistent with adrenocortical carcinoma.
In the arterial phase, ACC shows heterogeneous enhancement. Solid tumor components show moderate to avid enhancement, while necrotic/cystic areas do not enhance. Peripheral enhancement (rim enhancement) is common — viable peripheral tumor tissue + central necrosis. Enhancing tumor thrombus within invaded vessels (renal vein, IVC) may be seen.
Report Sentence
In the arterial phase, the lesion shows heterogeneous enhancement with large central necrotic areas remaining unenhanced; enhancing tumor thrombus extending to the ___ level is seen in the IVC.
On delayed phase, ACC shows slow washout (absolute <60%). However, reliable washout measurement is difficult in large heterogeneous lesions because necrosis and hemorrhage complicate ROI placement. Measurement should be performed on solid components.
Report Sentence
On delayed phase, slow washout is observed in the solid components of the lesion.
On T2-weighted images, ACC shows heterogeneous signal. Solid components show intermediate-to-high signal, necrotic/cystic areas are markedly hyperintense, hemorrhage areas show stage-dependent signal. MRI is superior to CT for evaluating tumor margins and invasion — especially IVC tumor thrombus extent.
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On T2-weighted images, the lesion shows heterogeneous signal with markedly hyperintense necrotic/cystic areas and intermediate hyperintense solid components.
ACC usually does not show chemical-shift signal loss — intracellular lipid is absent in malignant cells. However, in rare cases (5-10%) focal signal loss may be seen — this may be related to the tumor containing normal adrenal cortex remnants or heterologous lipomatous differentiation. ACC should not be excluded in the presence of focal signal loss.
Report Sentence
On chemical-shift sequences, no opposed-phase signal loss is seen in the lesion, consistent with a malignant adrenal mass.
On DWI, solid components of ACC show diffusion restriction. ADC values are low (0.6-1.2 × 10⁻³ mm²/s). ADC is high in necrotic/cystic areas. Low ADC reflects high cellularity and mitotic activity.
Report Sentence
On DWI, diffusion restriction is observed in solid components (ADC: ___ × 10⁻³ mm²/s), consistent with high cellularity.
On FDG PET-CT, ACC typically shows high FDG uptake (SUVmax usually >10). This reflects the tumor's high metabolic activity and aggressive biological behavior. PET-CT is valuable for staging (distant metastasis screening) and recurrence detection. SUVmax >10 is a strong indicator of malignancy.
Report Sentence
On FDG PET-CT, high FDG uptake is observed in the adrenal mass (SUVmax: ___), consistent with malignant lesion; distant metastasis screening should be evaluated.
Criteria
Hormone secretion present. Cortisol (30-40%), androgen (20-30%), estrogen (rare), aldosterone (rare). Mixed syndrome (multiple hormones) suspicious.
Distinct Features
Virilization (hirsutism, voice deepening in women), Cushing (central obesity, striae, hypertension), feminization (gynecomastia in men). Functional ACC usually detected earlier (symptoms).
Criteria
No or subclinical hormone secretion. Incidentally detected or presents with mass effect (abdominal pain, palpable mass).
Distinct Features
Detected later (no symptoms), therefore usually larger size and more advanced stage at diagnosis. Prognosis may be worse than functional ACC.
Criteria
In childhood. TP53 germline mutation common (Li-Fraumeni). 65% functional. Endemic in southern Brazil (R337H TP53 variant).
Distinct Features
Adrenal mass in children → differential between ACC and neuroblastoma is critical. Urine catecholamines (VMA/HVA) provide clue for neuroblastoma, hormonal profile for ACC. Prognosis generally better than adults.
Distinguishing Feature
Pheochromocytoma shows marked T2 hyperintensity ('light bulb'), elevated catecholamines, MIBG positive. ACC heterogeneous on T2, elevated steroid hormones (cortisol, androgen), MIBG negative.
Distinguishing Feature
Metastasis usually smaller (<6 cm), known primary malignancy. ACC usually >6 cm, may be functional (virilization, Cushing), primary adrenal malignancy.
Distinguishing Feature
Myelolipoma contains macroscopic fat (-30 to -100 HU), benign. ACC does not contain fat (rare exception), malignant, invasive.
Distinguishing Feature
Adrenal hemorrhage shows no enhancement (with mass effect), stage-dependent MRI signal, decreases in size over time. ACC contains solid enhancing component, grows, shows invasion.
Urgency
urgentManagement
surgicalBiopsy
Not NeededFollow-up
3-monthACC diagnosis requires urgent surgical management. Surgery (R0 resection) is the only curative treatment — open adrenalectomy is preferred (laparoscopic surgery carries risk of capsular rupture and local recurrence). Adjuvant mitotane (adrenolytic agent) is standard treatment in stage III and R1/Rx resection. In advanced/metastatic ACC, etoposide-doxorubicin-cisplatin + mitotane (EDP-M) regimen is used. ENSAT staging system is used. CT follow-up at 3-month intervals — recurrence risk is high (50-80% within 5 years). Hormonal markers are followed in functional ACC. Biopsy is generally not needed because size and imaging findings have diagnostic adequacy; additionally biopsy carries risk of tumor dissemination.
ACC is an aggressive tumor and early-stage surgical resection is the only curative treatment. Adrenal masses >4 cm carry high suspicion for ACC and should be evaluated for surgery. Hormonal assessment (cortisol, androgens) should be performed.