Perianal Granuloma Workup

Updated: Dec 01, 2022
  • Author: Burt Cagir, MD, FACS; Chief Editor: John Geibel, MD, MSc, DSc, AGAF  more...
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Laboratory Studies

Laboratory tests in patients with perianal granuloma are of help only after it has become obvious that the disease process is due to some unusual causative organism. In general, laboratory tests are not diagnostic in Crohn disease (CD).

The choice of laboratory tests is dictated by the clinical presentation, and results are more indicative of the degree of illness than of the etiology. [25]  When an unusual etiology for the disease process becomes apparent, directed investigative tests become useful.

Superficial wound cultures are usually of no diagnostic use and yield only colonizing bacteria (usually of skin or gastrointestinal [GI] tract origin) rather than true pathogens. However, biopsy of a nonhealing or recurrent wound with stains and culture of the tissue may yield identification.

Other tests that may be useful include the following:

  • Potassium hydroxide (KOH) preparation - Can help to identify yeast organisms
  • Acid-fast bacillus (AFB) staining - Although commonly performed in this setting, this usually yields negative results (tissue cultures produce a higher yield but take 7-21 days)
  • A Tzanck preparation - May be helpful in excluding herpes

Imaging Studies

Imaging tests that aid in the diagnosis and evaluation of causative diseases in perianal granuloma include the following:

  • Radiography - Should be obtained when the possibility of perianal tuberculosis is being evaluated; nearly all patients with perianal or anorectal tuberculosis have chest radiographic findings suggestive of old or active pulmonary tuberculosis
  • Barium enemas - May be used to evaluate the colorectal mucosa in the differential diagnosis of CD
  • Upper GI/small-bowel series - Used to evaluate the upper GI tract and terminal ileum for CD


Endoscopic evaluation may aid in obtaining material for pathology and culture. Proctoscopy is probably most useful. Sigmoidoscopy and colonoscopy can be helpful in the evaluation of inflammatory bowel disease (IBD) or in more proximal involvement of the colon with infectious agents.

Examination under anesthesia, with biopsy or scraping of wounds or ulcerations, can also yield material for diagnostic evaluation.


Histologic Findings

Regular histopathology should always be requested on tissue specimens. The presence of so-called sulfur granules is characteristic of Actinomyces. Granulomas, caseating or noncaseating, may be observed, though this is more rare in CD than is commonly believed. Other infectious agents (eg, fungi and parasites) may be identified with histopathology.