The aim of the pictorial review are to review the HIV manifestations within the gastrointestinal tract. We have detailed five conditions, with reference to the patients’ CD4 count – gastrointestinal tuberculosis, Kaposi’s sarcoma, small bowel lymphoma, cytomegalovirus colitis and anal carcinoma.
The acquired immunodeficiency syndrome (AIDS) was first described as a clinical entity in 1981, and HIV (human immunodeficiency virus) was identified as the causative organism in 1983.
Gastrointestinal pathology in HIV includes a number of rare infections and tumours related to immunosuppression. The gastrointestinal disease manifestations of HIV can be subdivided into two categories: Infections and HIV acquired neoplasm.
Cytomegalovirus Tuberculosis
Kaposi sarcoma Non-Hodgkin’s lymphoma Squamous cell carcinoma
The presentation of each disease is variable, the incidence increasing should the patients’ CD4 count fall below certain thresholds, as detailed below Kaposi sarcoma: < 350 cells/μL Anal carcinoma: < 350 cells/μL Non-Hodgkin’s lymphoma: < 200 cells/μL Tuberculosis: < 200 cells/μL Cytomegalovirus colitis: < 100 cells/μL
We have pictorially reviewed the various gastrointestinal manifestations in HIV, with reference to patients CD4 count.
We have focused specifically on small bowel lymphoma. The incidence of primary small bowel lymphoma is rare and is estimated to attribute to just 0.9% of all gastrointestinal tract tumours.
However, the incidence is increasing, primarily because of the increased rate of HIV. One study
Small bowel lymphoma typically involves the terminal ileum, and becomes less frequent proximally.
The radiological features of small bowel lymphoma include:
Focal thickening of the bowel wall, measuring between 1 and 7 cm Fungating masses Tumour infiltration of the myenteric nerve plexus, resulting in aneurysmal bowel dilatation Solid mass lesion (rare).
As demonstrated in
Coronal reconstruction of the portovenous phase of a CT abdomen of a 50-year-old male patient demonstrating lymphomatous circumferential thickening of terminal ileum and caecum (arrowed).
Coronal reconstruction of portovenous phase enhancement of a 50-year-old male (as
Cytomegalovirus (CMV) is a prevalent type of herpes simplex virus. CMV colitis is common, with an incidence of 5% – 10%, typically affecting the severely immunocompromised HIV patient.
The radiological features of CMV colitis are non-specific, and include bowel wall thickening, mucosal ulceration and luminal narrowing. It can be either diffuse or segmental, and typically involves the ascending colon and caecum, but can also extend to the terminal ileum. Unsurprisingly, CMV colitis is often misdiagnosed as inflammatory bowel disease.
Axial reconstruction of portovenous phase–enhanced CT, demonstrating circumferential mural thickening of the sigmoid colon (arrowed).
Coronal reconstruction of portovenous phase–enhanced CT, of the above patient, again demonstrating circumferential mural thickening of the sigmoid colon.
The main causative agent of anal squamous cell carcinoma is infection with the human papilloma virus (HPV). Although HIV is not a direct cause, it is an indicator of further co-infection of sexual transmitted diseases, particularly in patients engaging in anoreceptive intercourse.
MRI is the preferred imaging modality for the assessment of anal tumours, providing detailed information regarding size, location and local invasion. The malignant tissue within the anal canal demonstrates low signal intensity on T1-weighted imaging. On T2-weighted imaging and short tau inversion recovery (STIR) sequences, it appears as intermediate signal intensity, lower than ischioanal fat.
On CT, anal squamous cell carcinoma appears as a solid, enhancing mass, becoming more heterogeneous as its size increases
T2-weighted MR imaging, axial slice of a 42-year-old male patient, demonstrating a large anal soft tissue mass (arrowed) of intermediate signal intensity, with local soft tissue invasion. Histology confirmed the diagnosis of squamous cell carcinoma.
Sagittal T2-weighted MR imaging of a 42-year-old male patient (as shown in
Worldwide, tuberculosis (TB) is prevalent, particularly amongst patients with HIV, and it has been estimated that up to 70% of patients will develop TB in their lifetime.
Abdominal tuberculosis can affect any segment of the gastrointestinal tract but most commonly the terminal ileum
However, CT/MRI features are often non-specific, and can be confused with inflammatory bowel disease or malignancy. Asymmetric thickening of the terminal ileum and medial wall of the caecum Significant lymphadenopathy, with central areas of reduced attenuation.
Axial reconstruction of portovenous phase–enhanced CT in a 23-year-old male patient with a CD4 count of 70 cells/μL. The image demonstrates diffuse serosal thickening of the jejunum (dashed arrow), ascites and peritoneal nodularity (solid arrow). Histological diagnosis of TB was made following ascitic tap.
Coronal T2-weighted MRI. This image is of a 30-year-old male with a CD4 count of < 100 cells/μL, demonstrating a 4 cm segment of thickened distal and terminal ileum, with localised perforation. Confirmation of TB was made upon endoscopic biopsy and histology.
Kaposi sarcoma (KS) is considered to be an AIDS defining illness. Gastrointestinal KS is the most common involvement in disseminated disease, being identified in around half of the patients.
Portovenous-enhanced CT is the preferred imaging modality, with 80% of patients with disseminated disease demonstrating enhancing lymph nodes.
Axial reconstruction, portovenous-enhanced CT imaging of a 50-year-old male patient. The image demonstrates rectal thickening (dashed arrow) and an enhancing mesorectal node (solid arrow).
Axial T2-weighted MRI imaging. The patient is a 50-year-old male with thickening of the posterior wall of the rectum. MRI was performed to aid surgical management.
The gastrointestinal tract is a common location for many AIDS defining and non-defining illnesses. As detailed above, depletion of the patients CD4 count increases their likelihood of developing certain pathologies. In conditions such as CMV colitis and abdominal TB, the imaging features can be non-specific, with few subtle defining characteristics. An understanding of the disease processes associated with HIV, together with correlation with the patients CD4 count, aids diagnosis and management.
The authors declare they have no personal or financial relationship which may have influenced them in writing this article.
A.R. was the lead author and editor. F.K. was the lead consultant involved in the project, and contributed cases. N.K. contributed cases. B.R. was a contributing author. E.O. assisted in editing.