Diagnostic Ultrasound - Abdomen and Pelvis

Adrenal Carcinoma
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Diagnoses: Adrenal Gland
Infection
• Nonspecific; soft tissue masses with cystic changes ±
calcifications
• Tuberculins and histoblastomas usually bilateral but can be
asymmetric
Myelolipoma
• Typically hyperechoic on US; however, can be
heterogeneous when myeloid elements predominate and
can be large
• Easily recognizable on CT and MR due to macroscopic fat,
which is diagnostic
Adrenal Hemorrhage
• Heterogeneous on US depending on age of hemorrhage
• AC can contain hemorrhagic elements due to necrosis
• CT and MR show lack of enhancement
PATHOLOGY
General Features
• Etiology
○ Most ACs are sporadic
• Genetics
○ More likely to be aneuploid or tetraploid
○ Genetic syndromes can ↑ incidence of AC
– Beckwith-Wiedemann, Li-Fraumeni, Carney, familial
adenomatous polyposis, MEN1
Staging, Grading, & Classification
• Surgical staging system may offer better prognostic
accuracy than TMN staging
○ Stage I: Diameter ≤ 5 cm, no local invasion
○ Stage II: Diameter > 5 cm, no local invasion
○ Stage III: Any size + local invasion or nodes
○ Stage IV: Any size + local invasion & nodes or metastases
Gross Pathologic & Surgical Features
• Tumor weight > 500 g, grossly lobulated cut surface,
necrosis, calcification, and hemorrhage favor malignancy
Microscopic Features
• Architectural disarray, ↑ mitotic rate, nuclear
pleomorphism/atypia, hyperchromasia, capsular invasion,
and venous or sinusoidal invasion favor malignancy
• May contain intracytoplasmic lipid or macroscopic fat
○ Due to cortisol/related fatty precursors in hormonally
active tumors or coexisting myelolipomatous tissue
CLINICAL ISSUES
Presentation
• Most common signs/symptoms
○ 65-85% are nonfunctioning at presentation (adults)
– Large, palpable mass (40-50%)
□ Mass effect symptoms: Pain, fullness
– Incidental mass on imaging exam (0-25%)
– Late detection: 30% with metastases at presentation
• Other signs/symptoms
○ Functional tumors (85% of children; 15-30% of adults)
– Cushing syndrome (30-40%): ↑ cortisol
□ Moon facies, truncal obesity, striae, and buffalo
hump
– Virilization in females (20-30%): ↑ androgens
□ 95% of girls with functioning AC present with
virilization
– 10-20% present with Cushing syndrome & virilization
□ Cortisol & androgen cosecretion favors malignancy
– Conn syndrome (2%): 1° hyperaldosteronism
– Feminization in males (2%): ↑ androgens
– Other clinical syndromes: Hypoglycemia,
polycythemia, and nonglucocorticoid-related insulin
resistance
Demographics
• Age
○ Bimodal distribution
– < 5 years old (1st peak) and 30-50 years old (2nd peak)
• Gender
○ Slightly more common in women (M:F = 1:1.5)
○ Functioning: F > M; nonfunctioning: M > F
• Epidemiology
○ Rare: 0.05-0.20% of all cancers
○ 1 per 1,500 adrenal tumors is malignant
Natural History & Prognosis
• Rapid growth with local invasion and distant metastases
• Tumor thrombus: IVC and renal vein (best seen on MR)
• 5-year post-resection survival
○ Stage I and II: 65%; stage III: 40%; stage IV: 10%
• 5-year survival for pediatric ACs > adults (54% vs. 38%)
○ Pediatric ACs tend to be less aggressive
Treatment
• Definitive treatment for all stages: En bloc resection ±
adjacent invaded organs
○ Open adrenalectomy favored over laparoscopic
– High rate of recurrence/peritoneal carcinomatosis
associated with laparoscopic procedures
• Chemotherapy: Primary and adjuvant therapy
○ Mitotane = adrenolytic
• Radiotherapy: Local recurrence, incomplete/indeterminate
resection, bone metastases
DIAGNOSTIC CHECKLIST
Consider
• AC is rare; rule out common diagnoses
○ For example, adenoma, hemorrhage, neuroblastoma
• Differentiation may be difficult on US
Image Interpretation Pearls
• Large masses: More likely to be malignant (> 4 cm → 70%)
○ Excluding myelolipoma and pheochromocytoma, which
are usually recognizable
• Vascular invasion and IVC extension may be seen at
presentation
Reporting Tips
• IVC invasion (best depicted on MR; seen in 9-19% of cases)
is crucial for surgical planning
SELECTED REFERENCES
1. Ganeshan D et al: Current update on cytogenetics, taxonomy, diagnosis, and
management of adrenocortical carcinoma: what radiologists should know.
AJR Am J Roentgenol. 199(6):1283-93, 2012