Bladder, ureter & renal pelvis
Urothelial carcinoma - invasive
Microcystic


Topic Completed: 24 May 2021

Minor changes: 24 May 2021

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PubMed Search: Urothelial carcinoma microcystic

Megan L. Brown, M.D.
Maria Tretiakova, M.D., Ph.D.
Page views in 2021 to date: 171
Cite this page: Brown ML, Tretiakova M. Microcystic. PathologyOutlines.com website. https://www.pathologyoutlines.com/topic/bladdermicrocystic.html. Accessed June 20th, 2021.
Definition / general
  • Invasive urothelial carcinoma with deceptively bland architecture and cytology, consisting of slit-like or tubular microcysts lined by cuboidal / flattened cells with minimal atypia and intraluminal granular eosinophilic material (Mod Pathol 2009;22:S96)
Essential features
  • Very rare, predominantly case reports and small series (Histopathology 2014;64:872)
  • Main biologic significance is deceptively benign features, which may be mistaken for cystitis cystica or glandularis on small biopsies but is usually deeply invasive
  • Histologically may be distinguished by infiltrative growth pattern, as well as variability in cyst size and shape
Terminology
ICD coding
  • Location based ICD-10 coding:
    • Renal pelvis, including pelviureteric junction and renal calyces
      • C65.1 - malignant neoplasm of right renal pelvis
      • C65.2 - malignant neoplasm of left renal pelvis
      • C65.9 - malignant neoplasm of unspecified renal pelvis
    • Ureter, including ureteric orifice of bladder
      • C66.1 - malignant neoplasm of right ureter
      • C66.2 - malignant neoplasm of left ureter
      • C66.9 - malignant neoplasm of unspecified ureter
    • Bladder
      • C67.0 - malignant neoplasm of trigone of bladder
      • C67.1 - malignant neoplasm of dome of bladder
      • C67.2 - malignant neoplasm of lateral wall of bladder
      • C67.3 - malignant neoplasm of anterior wall of bladder
      • C67.4 - malignant neoplasm of posterior wall of bladder
      • C67.5 - malignant neoplasm of bladder neck
      • C67.6 - malignant neoplasm of ureteric orifice
      • C67.7 - malignant neoplasm of urachus
      • C67.8 - malignant neoplasm of overlapping sites of bladder
      • C67.9 - malignant neoplasm of bladder, unspecified
    • Other, unspecified urinary organs
      • C68.0 - malignant neoplasm of urethra
      • C68.1 - malignant neoplasm of paraurethral glands
      • C68.8 - malignant neoplasm of overlapping sites of urinary organs
      • C68.9 - malignant neoplasm of urinary organ, unspecified
Epidemiology
Sites
  • Bladder, renal pelvis
Pathophysiology
Etiology
  • No specific risk factors for development of microcystic variant reported
  • General risk factors for urothelial carcinoma: smoking, aromatic amine exposure, arsenic exposure
Clinical features
Diagnosis
  • Cystoscopy
  • CT scan
Laboratory
Radiology description
Prognostic factors
Case reports
Treatment
Gross description
  • Thickened bladder wall
Frozen section description
  • Not usually diagnosed on frozen section
  • Deceptively bland appearance; depth of invasion is key to distinguish from benign mimics, such as cystitis cystica glandularis, on the rare occurrence of frozen diagnosis (Eur Urol Focus 2020;6:653)
Microscopic (histologic) description
  • Invasive urothelial carcinoma with microcysts, macrocysts or tubular structures, lined by single to multilayered cuboidal or flattened cells with minimal cytologic atypia (Histopathology 2019;74:77)
  • Microcysts are irregular in shape, deeply infiltrative and range in size from microscopic to up to 2 mm (Histopathology 2019;74:77)
  • Has luminal granular eosinophilic secretions with necrotic cellular debris, sometimes mucinous material or a targetoid appearance (PAS+, Alcian blue+) (Mod Pathol 2009;22:S96, Arch Pathol Lab Med 2007;131:1244)
  • May be focally calcified
  • May be associated with nested variant of urothelial carcinoma
  • May be associated with focal high grade conventional urothelial carcinoma in approximately 40% of cases (Histopathology 2019;74:77)
Microscopic (histologic) images

Contributed by Megan L. Brown, M.D. and Maria Tretiakova, M.D., Ph.D.
Microcysts, macrocysts and tubules

Microcysts, macrocysts and tubules

Invasion to muscularis propria

Invasion to muscularis propria

Cytokeratin 7

Cytokeratin 7

Positive stains
Negative stains
Molecular / cytogenetics description
Sample pathology report
  • Bladder, transurethral resection:
    • Invasive high grade urothelial carcinoma with microcystic component (40%)
    • Invasive of muscularis propria (pT2)
    • Angiolymphatic invasion absent
Differential diagnosis
Board review style question #1

A 40 year old man presents with gross hematuria, abdominal pain and bladder wall thickening on CT scan. He undergoes transurethral resection of bladder tumor (see above image). Which immunohistochemical profile would support the diagnosis of urothelial carcinoma with microcystic features?

  1. PAX8- / GATA3- / CK7+ / PSA+
  2. PAX8- / GATA3+ / CK7+ / p53 wild type / PSA-
  3. PAX8- / GATA3+ / CK7+ / p53+ / PSA-
  4. PAX8+ / GATA3- / CK7- / PSA-
Board review style answer #1
C. PAX8- / GATA3+ / CK7+ / p53+ / PSA-. This immunohistochemical profile is one that is classic to conventional urothelial carcinomas and shared by microcystic variant.

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Reference: Microcystic urothelial carcinoma-invasive
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