Non-neoplastic Disorders of the Urinary Bladder

A) Von Brunn’s nests – Rounded well circumscribed groups of urothelial cells in the lamina propria with no atypia and sometimes with central lumina.

B) Cystitis glandularis – Similar to Von Brunn’s nests however with columnar cells and layers of urothelial cells. A normal finding. There may be intestinal metaplasia with goblets cells especially in the chronically irritated bladder eg: paraplegics, stones, LTC.

C) Cystitis cystica – Similar to Von Brunn’s nests however cystically dilated, lined by urotheliuma and contains eosinophilic proteinaceous material.

D) Squamous metaplasia – Keratinising form is associated with SCC, esp in the anterior wall and in those with chronic cystitis (non-functioning bladder, schistosomiasis. The Non keratinising glycogenated form is normal and found in the trigone and bladder neck in women.

E) Nephrogenic Adenoma – Tumour composed of small tubules resembling renal tubules. May have a tubular, cystic, polypoid, papillary or diffuse pattern. Atypia is rare.

F) Papillary hyperplasia – A herald lesion when the urothelium overlying inflammatory or neoplastic processes occasionally has a papillary appearance. The underlying lesion may originate in the prostate, female genital tract or colon.

G) Polypoid/Papillary/Bullous cystitits – Result from inflammation and oedema of the lamina propria. A spectrum.

  • Papillary – finger like papillae lined by reactive urothelium
  • Polypoid – broad based oedematous lesions
  • Bullous – when lesion is wider than tall

H) Follicular cystitis –  Nodules of lymphoid aggregates usually with germinal centers in the lamina propria. May be visible macroscopially as small domed shaped lesions on the mucosal surface.

I) Giant cell cystitis – Atypical mesenchymal cells with enlarged, hyperchromatic nuclei or multiple nuclei often with bipolar or multipolar tapering eosinophilic cytoplasmic processes. (DD post op spindle cell nodule, sarcomatoid urothelial carcinoma & sarcoma, post radiotherapy, post chemo)

J) Haemorrhagic cystitis – Post chemical toxins, radiation, viruses, idiopathic. Especially post cyclophosphamide – may lead to irreversible fibrosis with a small contracted bladder.

K) Interstitial cystitis – Marked frequency, urgency and pain when the bladder becomes full and when it is emptied. Ulceration (may be scars & muscle wall thickening), inflammation (mast cells, lymphocytes, plasma cells) and vascular congestion.

L) Eosinophilic cystitis – Inflammation consisting of abundant eosinophils, (assoc with TUR, inv Ca, also asthma, eosinophilic gastroenteritis, rarely allergy, parasites)

M) Post surgical necrobiotic granuloma – Post TUR, linear or serpiginous granulomas with central amorphous debris or necrosis with palisading epitheloid histiocytes.

N) Bacillus- Calmette Guerin granulomas – Post BCG instillation. Small granulomas with epitheloid histiocytes and MNGC.

O) Other non infectious granulomas – Xanthogranulomatous pyelonephritis, Xanthoma, Granulomatous disease of childhood, rheumatoid arthritis, Crohns, Sarcoidosis.

P) Radiation cystitis – 3-6/52 post tx. Loss of urothelium with congestion of the lamina propria. Nuclear atypia with vacuoles in the cytoplasm and nuclei with karyorrhexis. Hyalinised and thickened blood vessels. Atypical spindle cells.

Q) Reaction to chemotherapy – Thiotepa and mitomycin C. Denudation of the mucosa and nuclear atypia.

R) Infectious cystitis – Esp coliforms and structural predisposition due to exstrophy (incomplete closure of the bladder), urethral malformation, fistulae, diverticula, calculi & foreign bodies. Also in DM, CRF and immunosuppression, Acute inflammation, suppuration and exudation, abscess formation then granulation tissue and fibrosis. Most are ascending although TB tends to be descending from the kidney.

S) Gangrene – Necrotic tissue. May be deposition of mineral salts.

  • Encrusted cystitis – When urea splitting bacteria alkalinise the urine (esp Corynebacterium urealyticum – requires a selective medium for culture and longer incubation) inorganic salts are deposited (and Calcium may be visible)
  • Emphysematous cystitis – gas filled blebs may be due to E-coli and Aerobacter aerogenes.

T) Malakoplakia – Yellow white soft raised plaques on the mucosal surface. Accumulation of histocytes with granular eosinophilic cystoplasm with intracytoplasmic inclusions known as Michaelis Gutmann bodies. Typically spherical, concentrically laminated bodies which may contain calcium. A uncommon granulomatous process due to the impaired capacity of mononuclear cells to kill phagocytosed bacteria.

U) Post operative spindle cell nodule – Post op lesion. Heaped up tumour. Friable vegetant mass. Interlacing fascicles of mitotically active spindle cells although little pleomorphism or hyperchromasia.

V) Pseudosarcomatous fibromyxoid tumour (inflammatory pseudotumours) – Even without surgery – A benign proliferative spindle cell lesion that mimics sarcoma. Inflammation and vascularity is more prominent. FISH for ALK gene translocation and IHC for ALK1 may help.

W) Amyloidosis – Blood vessels and sometimes lamina propria

X) Condyloma acuminatum – HPV associated koilocytic changes

Y) Schistosomiasis – Eggs and ova may be seen with associated granulomatous inflammation

Reference: Urological Surgical Pathology. 2nd Ed. Boswick & Cheng.

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