Prostate gland & seminal vesicles


Granulomatous lesions

Topic Completed: 1 September 2016

Minor changes: 12 April 2021

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PubMed search: Prostatic granulomatous lesions

Ximing J. Yang, M.D., Ph.D.
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Cite this page: Yang XJ. Granulomatous lesions. website. Accessed December 8th, 2021.
Definition / general
  • A wide range of pathogenic agents cause granulomatous inflammation of the prostate including:
    • Infectious: Mycobacteria Calmette-Guérin (BCG) or Mycobacterium tuberculosis (TB); other bacterial and fungal organisms such as blastomycosis and cryptococcus (J Assoc Physicians India 2012;60:57), parasitic infestation such as schistosomiasis (Parasitol Res 2015;114:351); also viral (Herpes zoster) infection
    • Foreign body giant cell granuloma: induced by a foreign body, injection of foreign material, or prostatic secretion when leaking out the glandular structure
    • Procedure related: post-transurethral resection and post-needle biopsy granulomas (needle track) cause granulomatous inflammation; BCG granulomas are induced by intravesical installation of live BCG as a therapy for superficial bladder cancer (J Clin Diagn Res 2016;10:EC20)
    • Idiopathic: nonspecific granulomatous prostatitis is the most common granulomatous inflammation in the prostate (Yang: Atlas of Practical Genitourinary Pathology, First Edition, 2014); xanthogranulomatous prostatitis is also in this category (World J Surg Oncol 2006;4:30)
    • Systematic: Sarcoidosis, granulomatosis with polyangiitis (Wegener's) (Medicine (Baltimore) 2012;91:67), Churg-Strauss syndrome or allergic (eosinophilic) granulomatous prostatitis have been reported in the prostate but they are rare
    • Malignant neoplasms: adenocarcinoma or lymphoma of the prostate may be also associated with granulomatous information; inflammation may mask the presence of malignant cells

Classification of Granulomatous Inflammations of the Prostate

Granuloma Type Etiology Microbiologic Studies Special Histological Features in Addition to Granuloma
Infectious Bacterial Positive AFB in TB granuloma with caseating central necrosis and Langhans giant cells
Fungal Positive Presence of GMS positive organisms (spores or hyphae)
Parasitic Positive Presence of eggs or worms of parasites
Viral Positive Viral cytopathic effects or inclusions
Foreign body granulomas Injection or introduction of foreign material Negative Presence of foreign material or foreign body giant cells
Procedure related Transurethral resection of prostate (TURP) Negative Geographic fibrinoid necrosis
Needle core biopsy track Negative Small granuloma with central necrosis
BCG induced Positive Discrete granuloma with or without Langhans giant cells
Idiopathic (possibly caused by rupture of ducts) Nonspecific granulomatous prostatitis Negative Poorly defined multiple granulomas, often associated with glandular destruction
Xanthogranulomatous prostatitis or xanthoma Negative Presence of numerous foamy histiocytes
Systematic Sarcoidosis Negative Well defined granuloma, generally without caseating necrosis
Churg-Strauss Negative Significant eosinophil infiltrate associated with polyangiitis
Granulomatosis with polyangiitis (Wegener's) Negative Necrosing granuloma with polyangiitis
*Eosinophilic Negative Significant eosinophil infiltrate
Malakoplakia Malfunction of macrophages Negative Presence of Michaelis-Gutmann bodies

*Eosinophilic granuloma may be related to TURP or other procedures, parasite infection or unknown etiology
Clinical features
  • Vary by etiology: patients may have no symptoms
  • Patients may present with local symptoms such as urgency, frequency and dysuria or with systemic symptoms such as fevers or chills
  • Severe cases may have urinary obstruction
  • Serum PSA may be elevated
  • Transrectal ultrasound (TRUS) shows prostatic hypoechoic zones that resemble adenocarcinoma
  • Many cases were initially discovered by biopsies or TURP for lesions suspicious for carcinoma; granuloma may coexist with prostatic adenocarcinoma, sarcoma or lymphoma (J Urol 1987;138:320)
  • Asymptomatic cases typically require no treatment
  • Antibiotics for infections and steroids for systemic granulomas
  • Men with a firm nodular prostate on digital rectal examination or elevated serum PSA levels, which are clinically suspicious for carcinoma, may need prostate needle core biopsy
  • Simple prostatectomy or transurethral resection may be necessary to relieve obstructive symptoms
Gross description
  • Firm and nodular prostate but gross appearance is not specific
Microscopic (histologic) description
  • Common features: a granuloma is composed predominantly of histiocytes, surrounded by lymphocytes and other inflammatory cells - multinuclear giant cells and central necrosis may be present in some cases
  • Nonspecific granulomatous prostatitis: expansile nodular infiltrates usually involving entire lobules with epithelioid histiocytes, heavy lymphocytes, plasma cells, neutrophils and variable eosinophilic infiltrates (see Figures 1A and 1B); multinuclear giant cells are occasionally seen
  • Post-transurethral resection (TUR) granuloma: resembles rheumatoid nodules with central geographic fibrinoid necrosis, surrounded by palisaded histiocytes and frequent multinucleated giant cells
  • BCG granuloma: well defined multiple granulomas, variable caseating necrosis and Langhans giant cells
    • Since AFB stain identifies acid-fast bacilli in only 1/3 of cases, it is rarely used in a patient with a history of BCG treatment (see Figure 2)
  • Foreign body granuloma composed of foreign material and granulomatous inflammation (see Figure 3)
  • Allergic: granulomas surrounded by palisaded histiocytes with heavy eosinophilic infiltrates
  • There are considerable histological overlaps between different types of granulomas, so that a granuloma with any special feature described above can be diagnosed as an “indeterminate granuloma” (see Figure 4)
Microscopic (histologic) images

Contributed by Ximing J. Yang, M.D., Ph.D.

Figure 1A (left) and Figure 1B (right)

Figure 2

Figure 3

Figure 4

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