What is hiding in the hindgut sac? Looking beyond rectal carcinoma

Virmani, Vivek; Ramanathan, Subramaniyan; Virmani, Vineeta Sethi; Ryan, John; Fasih, Najla

doi:10.1007/s13244-014-0347-z

Insights into Imaging

Table 1 Summary of characteristic CT and MRI features of various rectal lesions

From: What is hiding in the hindgut sac? Looking beyond rectal carcinoma

Lesion		CT features	T1-weighted MRI	T2-weighted MRI	Gadolinium	DWI	ADC	Comments
DEVELOPMENTAL	Tail gut cyst	Multilocular cystic lesion	Hypointense	Hyperintense	Peripheral enhancement	Hyperintense	Hyperintense	Variable T1 and T2 signal due to proteinaceous, mucus and blood products
	Duplication cyst	Unilocular cystic lesion	Hypointense	Hyperintense	Peripheral enhancement	Hyperintense	Hyperintense	Presence of muscle layer and rectal communication
	Epidermoid cyst	Unilocular cystic lesion	Hypointense	Hyperintense	Peripheral enhancement	Hyperintense	Hypointense	Presence T2 hypointense keratin and diffusion restriction
	Dermoid cyst	Unilocular cystic lesion with fat attenuation	Hyperintense	Isointense to hyperintense	Peripheral enhancement	Hyperintense	Hypointense	Hypointense on fat suppression T1 MRI
BENIGN NEOPLASMS	Lipoma	Soft tissue mass with fat attenuation	Hyperintense	Isointense to hyperintense	Mild to variable	Hyperintense	Hypointense	Hypointense on fat suppression T1 MRI
	Leiomyoma	Soft tissue mass	Isointense to hypointense	Isointense to hyperintense	Mild to variable	Variable	Variable
	Villous adenoma	Carpet or cauliflower like polypoid mass	Hypointense	Hyperintense	Moderate	Hyperintense	Isointense	Enhancement of fibrovascular core
	Schwannoma	Homogenous soft tissue mass	Isointense to hypointense	Hyperintense	Mild homogenous	Isointense to hyperintense	Isointense
	Cavernous haemangioma	Heterogenous rectal wall thickening with perirectal soft tissue	Isointense to hypointense	Hyperintense	Intense heterogenous	Hyperintense	Isointense to hyperintense	Serpiginious vascular structures and perirectal soft tissue extension
MALIGNANT NEOPLASMS	Mucinous (colloid) carcinoma	Heterogenous hypodense mass	Hypointense	Hyperintense	Heterogenous	Hyperintense	Hypointense	High T2 signal and lace like enhancement
	Lymphoma	Polypoidal mass or diffuse wall thickening	Isointense	Hyperintense	Mild to moderate homogenous	Hyperintense	Hypointense	Aneurismal dilatation and bulky perirectal adenopathy
	Stromal tumours (GIST)	Eccentric soft tissue mass	Hypointense	Isointense to hyperintense	Moderate heterogenous	Hyperintense	Hypointense	Necrosis and haemorrhage seen. Absence of perirectal adenopathy
	Neuro-endocrine tumours	Polypoidal mass	Isointense	Isointense to hyperintense	Marked homogenous	Variable	Variable
	Anorectal melanoma	Polypoidal fungating mass	Isointense to hyperintense	Isointense to hypointense	Variable	Variable	Variable	Perirectal infiltration and bulky lymph nodes
	Kaposi sarcoma	Polypoidal mass or irregular fold thickening	Isointense to hypointense	Hyperintense	Moderate heterogenous	Variable	Variable	Bulky lymphadenopathy and intratumoral haemorrhage
	Linitis plastica	Long segment circumferential thickening	Hypointense	Concentric ring pattern	Moderate	Variable	Variable	Target sign on CT and concentric ring on MRI
MISCELLANEOUS	Deeply infiltrating endometriosis (DIE)
	Irregular rectal wall thickening	Isointense to hyperintense	Hypointense	Variable heterogenous	Variable	Variable	Spiculation and retraction of rectal wall
	Lymphogranuloma venerum (LGV)
	Smooth circumferential wall thickening	Hypointense	Isointense to hyperintense	Variable	Isointense to hyperintense	Isointense	Smooth strictures with intact mucosa
	Stercoral colitis	Faecal impaction with wall thickening	Isointense	Isointense to hyperintense	Variable	Hyperintense	Hyperintense	Dense mucosa and perirectal stranding
	Pseudo myxoma retroperitonei	Septated cystic lesions with mural nodules and calcifications	Hypointense	Hyperintense	Peripheral, solid and septal enhancement	Hyperintense	Hyperintense	History of surgery for mucinous neoplasm

CT computed tomography, MRI magnetic resonance imaging, DWI diffusion-weighted imaging, ADC apparent diffusion coefficient

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