This case report followed CARE guidelines.
A 71-year old female patient, white homemaker, married, born and residing in Santo Andre (Sao Paulo, Brazil), reported pain during evacuation, fecal incontinence, and wounds in the perianal and intergluteal region for two years, associated with weight loss of 20 kg in the last year. She reported daily bowel movement, without evacuation effort, with neither blood nor mucus in her stool. The patient had no cough, afternoon fever, or night sweats. The patient was hypertensive, no previous surgeries, and had no history of family members with TB or contact with people with TB. The patient had a history of eight normal childbirths. There was a slight pallor on physical examination, with no other abnormalities. Her BMI was 31. The proctological inspection showed a lesion in the intergluteal region, ulcerated and hyperemic, with raised borders, 10 cm in length, indurated, and intensely painful to touch. In the perianal area, there were deep circumferential ulcers that affected the anterior and posterior quadrants of the anal circumference and fistulous perianal tracts with an outflow of seropurulent secretion. The rectum was intensely painful to the touch. During the colonoscopy, the device progressed to the cecum with visualization of the cecal ileum valve and terminal ileum without alterations, but there was pancolonic diverticular disease.
An abdominal and pelvic ultrasound was normal. Chest radiography, computed tomography (CT) of the abdomen and chest, and abdominal and pelvic magnetic resonance did not show relevant alterations. The purified protein derivative (PPD) and sputum alcohol-resistant bacilli tests were negative, as was the serology for HIV detection. However, the polymerase chain reaction (PCR) test on blood was positive for M. tuberculosis. The patient underwent a proctological examination with narcosis. Anoscopy revealed the presence of ulcers up to 2 mm in length, with stenosis 1cm from the anal edge and deep ulcers in the anterior and posterior region of the anal canal with exposure of the sphincter muscle. Biopsies of the intergluteal lesion and anal canal ulcers and a first-time fistulotomy using seton were performed. The anatomopathological examination of biopsies of the perianal region and the intergluteal lesion revealed a chronic granulomatous inflammatory process with mucosal ulceration, and tests for alcohol-acid-resistant fungi and bacilli were negative. The patient underwent a new proctological examination with narcosis and a second stage of fistulotomy. We performed biopsies of the anal fistula tract and perianal tissue. The pathological analysis (Fig. 1) revealed an epithelioid granulomatous process with multinucleated giant cells and granulation tissue in the intergluteal sulcus and the squamous tissue obtained from the perianal fistula tract.
Tests for fungi using Grocott-Gomori staining and for alcohol-acid-resistant bacilli using Ziehl-Neelsen and Fite-Faraco stains and a culture for M. tuberculosis were negative.
PCR is a simple and rapid test used for detection of M. tuberculosis because it amplifies a DNA sequence which is unique to mycobacteria (15). Pretreatment of tissue samples from biopsies of the intergluteal lesion and fistula tract was performed using the standard preparation method for laboratory diagnosis of mycobacteria (2.5% N-acetyl-L-cysteine-NaOH solution and decontamination by Kirchner's solution). Perineal tissues were immediately incubated at 80 C for 10 minutes. Then the samples were concentrated by centrifugation at 5000 x g for 5 minutes. The pellet was used for DNA extraction. Total DNA was extracted from the samples using Taqman  Real kit -Time PCR Assays (Thermo Fisher Scientific, Waltham, MA, USA) according to the procedure provided in the kit protocol. The DNA pellet was reconstituted in 20 microL of distilled water and stored at -20 C. The assay detects a 123 bp region of the M. tuberculosis complex-specific insertion sequence IS6110. Briefly, PCR amplification was performed to detect M. tuberculosis using a direct primer (5'-CCT GCG AGC GTA GGC GTC GGT-3') and primer reverse (5'-CTC CTC CAG CCC CCC CTT CCC-3'). PCR reactions were performed in a final volume of 25 microL containing 10 mM Tris-HCl (pH 8.3), 50 mM KCl, 2.5 mM MgCl2, 0.01% gelatin, 0.2 mM (each) of deoxynucleoside triphosphate, 1 mM each of forward and reverse primers and 1 U of Taq DNA polymerase. The PCR system 2700 thermal cycler (Applied Biosystem Inc, Foster City, CA, USA) was programmed to initially incubate the samples for 2 min at 94 C, followed by 35 cycles consisting of 94 C for 45 seconds, 53 C for 45 seconds and 72 C for 1 minute. The final extension was given at 72 C for 10 minutes. The specific detection of M. tuberculosis DNA was identified by specific bands of 123 bp of DNA on a 2% agarose gel, stained with ethidium bromide, and evaluated in a UV transilluminator. PCR product sizes were estimated according to the migration pattern of a 100 bp DNA ladder. The PCR test for M. tuberculosis in the intergluteal tissue was positive, but this test was negative in the material from the fistula tract.
The patient was treated with the RIPE regimen (isoniazid, rifampicin, ethambutol, and pyrazinamide). However, she discontinued treatment after 2 weeks due to the appearance of nausea, vomiting, and erythema throughout the body. After this clinical picture improved, we reintroduced the RIPE regimen for 6 months. After the end of the tuberculostatic regimen, the patient's examination revealed that the intergluteal fold had granulation tissue and no secretion (Fig. 2). The rectal examination was painless, with no fistulas or fissures. The patient maintains effortless evacuation of pale stools 2 to 3 times a day without proctological complaints.