Tuberculous Extra Pulmonary sites

  

 Tuberculous Extra Pulmonary sites ?? 

Sites of Extra-pulmonary tuberculosis are  1) lymphatic, 2) genitourinary,3) bone and joint, 4) miliary, and  5) meningeal tuberculosis & 6) Intestinal/ abdominal Tuberculosis (TB) is a chronic granulomatous disease caused by Mycobacterium tuberculosis. The usual site of infection is the lung, but other organs may be involved.

Abdominal tuberculosis represents the sixth most frequent form of Tuberculous bacteria reach the gastrointestinal tract via hematogenous spread, ingestion of infected sputum, or contiguous spread from adjacent organs. Almost all cases of abdominal TB are caused by Mycobacterium tuberculosis.. The predilection of the bacillus for the ileocecum, is attributed mainly to three factors: Relative physiological stasis of the area, the high rate of absorption, with more complete digestion (permitting free contact of the organism with the mucosal lining), and the abundance of lymphoid tissue at this site. There are three gross morphological forms of tuberculous enteritis: Ulcerative, hypertrophic, and ulcerohypertrophic. The ulcerative type, which commonly affects the ileum and jejunum, is characterized by a single or multiple transverse ulcers, the healing of which leads to stricture formation, and may perforate, bleed, or form fistulas. The hypertrophic and ulcerohypertrophic types commonly affect the ileocecum and cause obstruction or present as a mass. Grossly, peritoneal tubercles and enlarged, matted, caseous mesenteric lymph nodes may be seen .Microscopically, numerous, large, confluent granulomas of variable size, composed of epithelioid cells, with a peripheral zone of lymphocytes and Langhan's giant cells with central caseous necrosis, and surrounding fibrosis are seen. These ‘caseating granulomas’ are a characteristic histological feature of tuberculosis. Lesions are seen mainly in the submucosal and serosal layers. Sometimes, granulomas with caseation are seen only in the regional lymph nodes.

Perforation is a serious complication of abdominal TB, associated with high morbidity and mortality.

 The low incidence of tuberculous perforation is due to reactive fibrosis of the peritoneum .However, in recent years, intestinal perforation, which was relatively rare in the past, has been reported more frequently. The cause of this remains unknown.

Vasculitis is a well-established feature of tuberculosis of the central nervous system (CNS), lungs, and kidneys, but scarcely described in intestinal tuberculosis. Few studies have evaluated the role of mesenteric vasculitis in the natural history of intestinal tuberculosis. Ischemic changes have been said to underlie perforation and stricture formation.