Diagnostic Ultrasound - Abdomen and Pelvis
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Diagnostic Ultrasound - Abdomen and Pelvis

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09.07.2019 Views

Adrenal Carcinoma TERMINOLOGY Synonyms • Adrenocortical carcinoma (ACC); adrenal cancer Definitions • Malignant neoplasm arising from adrenal cortex IMAGING General Features • Best diagnostic clue ○ Large, heterogeneous, unilateral solid mass with local invasion (inferior vena cava [IVC] invasion) and metastases • Location ○ Suprarenal, 90-98% unilateral (left slightly > right gland) ○ Metastases: Liver, lung, regional lymph nodes, bone • Size ○ Large (average size: 9 cm; 70% > 6 cm) – Functioning tumors usually smaller (≤ 5 cm) than nonfunctioning tumors (≥ 10 cm) at presentation • Morphology ○ Typically well defined with aggressive-appearing features – Size > 4 cm, irregular margins, intratumoral necrosis/hemorrhage, calcification, heterogeneous enhancement, regional/venous invasion → IVC invasion (9-19% cases at presentation) ○ Displaces adjacent structures: Compresses kidney Ultrasonographic Findings • Grayscale ultrasound ○ Small tumors: Homogeneous, hypoechoic, similar to renal cortex ○ Large tumors: Heterogeneous, hypoechoic/anechoic areas (necrosis &/or hemorrhage), and echogenic ○ Scar sign: Predominantly echogenic pattern with radiating linear echoes; suggests carcinoma • Color Doppler ○ Invasion/occlusion of adrenal vein, renal vein, and IVC; ± intraluminal tumor thrombus CT Findings • NECT: Rarely attenuate < 10 HU (98% specificity for identifying benign adenomas) • CECT: Retain IV contrast material with absolute and relative washout of < 60% and < 40%, respectively, at 15 min ○ Heterogeneous, primarily peripheral enhancement due to central necrosis and hemorrhage – Necrosis invariably present in tumors ≥ 6 cm ○ Mass effect ± regional invasion, IVC thrombus, metastatic disease – Nodes, liver, lungs, bone • Calcifications (30%); coarse or micro, usually central MR Findings • T1WI: Predominately isointense/hypointense to liver parenchyma; often heterogeneous (necrosis) ○ High T1 signal indicates hemorrhage • T2WI: Hyperintense to liver parenchyma; heterogeneous • T1WI C+: Avid enhancement with delayed washout • Chemical shift imaging ○ Functioning tumors may contain small regions of intracytoplasmic lipid → small, nonuniform areas of signal loss (< 30% of lesion) – Similar pattern seen in lipid-poor adenomas – Not seen: Uniform signal loss (i.e., lipid-rich adenomas) • MR spectroscopy: Potential for distinguishing adenomas, pheochromocytomas, ACCs, and metastases Nuclear Medicine Findings • FDG PET combined with CECT ○ Sensitivity of 100% and specificity of 87-97% for identifying malignant adrenal masses ○ Detection of distant metastases (present in 1/3 of patients at presentation) • Novel PET tracer 11C metomidate for adrenocortical tissue ○ Uptake seen in adenomas and ACCs but not in pheochromocytomas and metastases Imaging Recommendations • Best imaging tool ○ CT or MR for complete characterization – US (initial screening) ○ MR is superior to CT in delineating invasion of IVC, renal vein, and interface with adjacent kidney/liver • Study of choice to exclude adenoma: NE + CECT DIFFERENTIAL DIAGNOSIS Pheochromocytoma • Can be large and heterogeneous, similar to adrenal carcinoma (AC) ○ Less commonly shows calcification, seen in 10% • 91% are functional → recognized biochemically • Bilateral in multiple endocrine neoplasia (MEN) 2A and 2B (not MEN1) Adrenal Metastases • Most common adrenal malignancy • Consider if bilateral involvement and known 1° present ○ Lung is most common primary Adrenal Adenoma • Small ACs can appear well defined and homogeneously hypoechoic • Adenoma rarely shows calcification • May be distinguished by CT washout and chemical shift imaging (sensitivity 75-98%; specificity 92-100%) Adrenal Lymphoma • Most commonly: Non-Hodgkin diffuse large B cell • Large, bilateral masses maintain adeniform shape Ganglioneuroma • In children and young adults (60% before 20 years) • CECT: Large solid lesion with homogeneous enhancement • MR: T2 heterogeneous hyperintensity, T1 C+ shows late gradual enhancement • Punctate or discrete calcification; no vessel involvement Neuroblastoma • Pediatric population; calcification is hallmark Diagnoses: Adrenal Gland 603

Adrenal Carcinoma 604 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

Adrenal Carcinoma<br />

TERMINOLOGY<br />

Synonyms<br />

• Adrenocortical carcinoma (ACC); adrenal cancer<br />

Definitions<br />

• Malignant neoplasm arising from adrenal cortex<br />

IMAGING<br />

General Features<br />

• Best diagnostic clue<br />

○ Large, heterogeneous, unilateral solid mass with local<br />

invasion (inferior vena cava [IVC] invasion) <strong>and</strong><br />

metastases<br />

• Location<br />

○ Suprarenal, 90-98% unilateral (left slightly > right gl<strong>and</strong>)<br />

○ Metastases: Liver, lung, regional lymph nodes, bone<br />

• Size<br />

○ Large (average size: 9 cm; 70% > 6 cm)<br />

– Functioning tumors usually smaller (≤ 5 cm) than<br />

nonfunctioning tumors (≥ 10 cm) at presentation<br />

• Morphology<br />

○ Typically well defined with aggressive-appearing<br />

features<br />

– Size > 4 cm, irregular margins, intratumoral<br />

necrosis/hemorrhage, calcification, heterogeneous<br />

enhancement, regional/venous invasion → IVC<br />

invasion (9-19% cases at presentation)<br />

○ Displaces adjacent structures: Compresses kidney<br />

Ultrasonographic Findings<br />

• Grayscale ultrasound<br />

○ Small tumors: Homogeneous, hypoechoic, similar to<br />

renal cortex<br />

○ Large tumors: Heterogeneous, hypoechoic/anechoic<br />

areas (necrosis &/or hemorrhage), <strong>and</strong> echogenic<br />

○ Scar sign: Predominantly echogenic pattern with<br />

radiating linear echoes; suggests carcinoma<br />

• Color Doppler<br />

○ Invasion/occlusion of adrenal vein, renal vein, <strong>and</strong> IVC; ±<br />

intraluminal tumor thrombus<br />

CT Findings<br />

• NECT: Rarely attenuate < 10 HU (98% specificity for<br />

identifying benign adenomas)<br />

• CECT: Retain IV contrast material with absolute <strong>and</strong> relative<br />

washout of < 60% <strong>and</strong> < 40%, respectively, at 15 min<br />

○ Heterogeneous, primarily peripheral enhancement due<br />

to central necrosis <strong>and</strong> hemorrhage<br />

– Necrosis invariably present in tumors ≥ 6 cm<br />

○ Mass effect ± regional invasion, IVC thrombus,<br />

metastatic disease<br />

– Nodes, liver, lungs, bone<br />

• Calcifications (30%); coarse or micro, usually central<br />

MR Findings<br />

• T1WI: Predominately isointense/hypointense to liver<br />

parenchyma; often heterogeneous (necrosis)<br />

○ High T1 signal indicates hemorrhage<br />

• T2WI: Hyperintense to liver parenchyma; heterogeneous<br />

• T1WI C+: Avid enhancement with delayed washout<br />

• Chemical shift imaging<br />

○ Functioning tumors may contain small regions of<br />

intracytoplasmic lipid → small, nonuniform areas of signal<br />

loss (< 30% of lesion)<br />

– Similar pattern seen in lipid-poor adenomas<br />

– Not seen: Uniform signal loss (i.e., lipid-rich<br />

adenomas)<br />

• MR spectroscopy: Potential for distinguishing adenomas,<br />

pheochromocytomas, ACCs, <strong>and</strong> metastases<br />

Nuclear Medicine Findings<br />

• FDG PET combined with CECT<br />

○ Sensitivity of 100% <strong>and</strong> specificity of 87-97% for<br />

identifying malignant adrenal masses<br />

○ Detection of distant metastases (present in 1/3 of<br />

patients at presentation)<br />

• Novel PET tracer 11C metomidate for adrenocortical tissue<br />

○ Uptake seen in adenomas <strong>and</strong> ACCs but not in<br />

pheochromocytomas <strong>and</strong> metastases<br />

Imaging Recommendations<br />

• Best imaging tool<br />

○ CT or MR for complete characterization<br />

– US (initial screening)<br />

○ MR is superior to CT in delineating invasion of IVC, renal<br />

vein, <strong>and</strong> interface with adjacent kidney/liver<br />

• Study of choice to exclude adenoma: NE + CECT<br />

DIFFERENTIAL DIAGNOSIS<br />

Pheochromocytoma<br />

• Can be large <strong>and</strong> heterogeneous, similar to adrenal<br />

carcinoma (AC)<br />

○ Less commonly shows calcification, seen in 10%<br />

• 91% are functional → recognized biochemically<br />

• Bilateral in multiple endocrine neoplasia (MEN) 2A <strong>and</strong> 2B<br />

(not MEN1)<br />

Adrenal Metastases<br />

• Most common adrenal malignancy<br />

• Consider if bilateral involvement <strong>and</strong> known 1° present<br />

○ Lung is most common primary<br />

Adrenal Adenoma<br />

• Small ACs can appear well defined <strong>and</strong> homogeneously<br />

hypoechoic<br />

• Adenoma rarely shows calcification<br />

• May be distinguished by CT washout <strong>and</strong> chemical shift<br />

imaging (sensitivity 75-98%; specificity 92-100%)<br />

Adrenal Lymphoma<br />

• Most commonly: Non-Hodgkin diffuse large B cell<br />

• Large, bilateral masses maintain adeniform shape<br />

Ganglioneuroma<br />

• In children <strong>and</strong> young adults (60% before 20 years)<br />

• CECT: Large solid lesion with homogeneous enhancement<br />

• MR: T2 heterogeneous hyperintensity, T1 C+ shows late<br />

gradual enhancement<br />

• Punctate or discrete calcification; no vessel involvement<br />

Neuroblastoma<br />

• Pediatric population; calcification is hallmark<br />

Diagnoses: Adrenal Gl<strong>and</strong><br />

603

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