Colonic Malakoplakia

Clinical History

A 58 year old patient presenting with 2 month history of left iliac fossa pain, wright loss and change in bowel habit.

Imaging Findings

The 68 year old male patient presented with a 2 month history of left ileac fossa abdominal pain, weight loss, and change in bowel habit. Previously he had a history of 2 cerebrovascular accidents, hypertension, previous treated gastric ulcer and Barrett’s oesophagus. On presentation, clinical examination was essentially normal with biochemically elevated C-Reactive Protein (CRP) at 147 mg/dL.

A barium enema examination revealed a tight and obstructing 8cm long stricture at the mid-sigmoid colon (Figure 1) which subsequent flexible sigmoidoscopy comfirmed. Due to the uncertain aetiology CT was performed which confirmed an abnormal 10cm length of sigmoid colon, some mild sigmoid diverticulosis with observed thickening of the bowel wall and pericolic fat streaking. No associated extra-colonic abnormalities were noted, specifically no evidence of pathological lymphadenopathy, however the appearances were suggestive of a malignant stricture (Figure 2). Subsequently, the patient underwent a left hemi-colectomy, appendicectomy, and cystoscopy with bilateral ureteric stenting, due to perceived bladder involvement at the time of surgery. Intra-operative frozen section histology showed dense inflammatory cells with no carcinoma present. Formal histological analysis was conducted based on the colonic specimen. Macroscopically, serial slicing revealed a single diverticulum. On microscopy collections of macrophages, some with inclusions, interspersed with mildly proliferative spindle cells representing stromal myelofibroblasts. A small abscess was identified adjacent to the colonic mass and associated mesocolonic lymph nodes showed reactive changes only. Essentially, histology features suggested malakoplakia, with the diverticular abscess as a source of chronic bacterial infection, with no evidence of malignancy

Discussion

Malakoplakia is a chronic granulomatous inflammatory condition, most commonly described involving the genito-urinary tract but can also affect gastro-intestinal, brain, tonsillar, thyroid, lung, skin, adrenal and bone tissues [1]. Malakoplakia affects the gastrointestinal tract in 10% of cases, making this the second most common site of involvement, compared to the GU tract in which is affected in 75% of cases[2]. Histiologically, malakoplakia is characterized by the presence of Michaelis-Gutmann bodies or histiocytic infiltrates concentrically layered with intracytoplasmic inclusions, initially recognized in 1902 (Michaelis Gutman) and subsequently named in 1903 deriving from the greek for ‘soft’ (malakos) and plaque (plakos).

Colonic malakoplakia was first described in 1965 [3] and reported cases since have recognised isolated malakoplakia as well as coexistent adenocarcinoma and inflammatory bowel disease and we report an association with diverticular disease and abscess formation [4, 5]. Malakoplakia can affect a wide age range from 6 weeks to 90 years of age [6] with an apparently bimodal distribution in the reported cases of colonic malakoplakia [4]. Colonic malakoplakia affects males more than females with a ration of 2:1 and the most common colonic sites for involvement are rectum, sigmoid and descending colon [7]. Causative aetiology remains uncertain, but there is growing evidence of a causative relationship to underlying chronic bacterial infection as well as altered host macrophage and immune responses. Associated micro-organisms include Staphylococcus Aureus, Proteus Mirabilis, Klebsiella, Mycobacterium and parasites, but most commonly Escherichia Coli, reportedly in 72% of cases [8]. Further additional factors which may be involved in the development of malakoplakia include immunosupression, with increased incidence amongst immunosupressed patients, and altered immune response, specifically macrophage function and bacterial elimination deficiencies [9]. Co-existent diverticular disease and abscess formation may present an opportunity for the development of malakoplakia secondary to chronic bacterial infection.

Clinically malakoplakia tends to present as three distinct types; focal lesions, mucosal lesions or large masses [10] and can deliver a diagnostic challenge and mimic neoplasia in a variety of ways. As described in this case, appearances can be misleading, particulary when malakoplakia presents as a large focal mass and demonstrates localized invasion to adjacent tissues.

Differential Diagnosis List

Final Diagnosis

Colonic malakoplakia with diverticular abscess.

URL:	https://www.eurorad.org/case/6385
DOI:	10.1594/EURORAD/CASE.6385
ISSN:	1563-4086