Bladder - Urothelial carcinoma - microcystic variant

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Bladder

Urothelial carcinoma

Microcystic variant

Reviewer: Rugvedita Parakh, Cedars-Sinai Medical Center, Los Angeles, California

Revised: 13 June 2011, last major update June 2010

Definition

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● Predominant features of urothelial carcinoma, but with prominent inter- or intracellular lumens and no true glands

Terminology

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● Considered equivalent to urothelial carcinoma with gland-like lumina by AFIP authors (Murphy: Tumors of the Kidney Bladder and Related Urinary Structures, AFIP Atlas of Tumor Pathology, Series 4, Vol 1, 2004, p 283); but WHO appears to make a minor distinction (Eble: Pathology and Genetics of Tumours of the Urinary System and Male Genital Organs, WHO 2004, p 99)

Etiology

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● Cyst-like structures may be due to ability of urothelium to form and line spaces (as occurs in bladder)

● May also be due to cell degeneration (based on presence of luminal debris and necrotic cells)

Clinical features

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● Uncommon variant associated with high stage and high grade tumors (Br J Urol 1997;79:722)

● Report as “urothelial carcinoma with microcystic differentiation”

Case reports

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● 80 year old man with microcystic tumor that also had gland-like lumina and signet-ring cell differentiation (Diagn Pathol. 2008 Sep 3;3:36)

● Microcystic histology in penile metastasis (Pathol Res Pract 2009;205:568, Pathol Oncol Res 2007;13:170)

Micro description (Histopathology)

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● Prominent intercellular or intracellular lumens / microcysts surrounded by neoplastic urothelial or squamous cells

● Lumens are usually empty, but may contain granular eosinophilic debris, necrotic cells or mucin

● Cysts vary in size, are round/oval, up to 2 mm; are lined by urothelium, flattened cells or low columnar cells, but not colonic epithelium or goblet cells (Am J Clin Pathol 1991;96:635)

● Cysts are infiltrative and may invade the muscularis propria

● Pattern resembles cystitis glandularis et cystica

● Also elongated, irregular branching spaces

● May rarely have neuroendocrine differentiation (Virchows Arch 2009;454:223)

Micro images

Cysts vary in size and grow irregularly Small cyst with luminal bulls-eye

in the lamina propria secretion

Tumors of renal pelvis Nodal metastasis has large, irregular

and ramified cysts

Urothelial carcinoma with gland-like lumina (H&E and Alcian blue)

Urothelial carcinoma with gland-like lumina (H&E and mucicarmine)

Lumens contain PAS+ material

CK20+

Differential Diagnosis

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● Adenocarcinoma: diffusely lined by goblet cells or intestinal cells, not flattened urothelial-like cells; usually deeply invasive, high grade

● Cystitis cystica / glandularis: glands in lamina propria lined by columnar, cuboidal or intestinal epithelium; no atypia, mitotic figures or necrosis

● Mucoid cytoplasmic inclusions: present in up to 37% of urothelial carcinomas, often high grade (Hum Pathol 1992;23:860)

● Nephrogenic metaplasia / adenoma: small hollow tubules similar to mesonephric tubules, usually lined by single layer of bland cuboidal or hobnail cells, surrounding eosinophilic or basophilic secretions; typically not cystic, no/minimal atypia or mitotic figures; no true invasion

● Müllerianosis: presence of 2 of 3 (endocervicosis, endometriosis or endosalpingiosis); no atypia, no mitotic figures

● Urothelial carcinoma with glandular differentiation: similar, but has true glands lined by goblet cells or colonic epithelium; is primarily a urothelial tumor, in contrast to adenocarcinoma

● Urothelial carcinoma, nested variant: may have focal tubular differentiation

End of Bladder > Urothelial carcinoma > Microcystic variant

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