IN DEPTH ASSESMENT OF VARIOUS IMAGING APPEARANCES OF GIT LYMPHOMA WITH BRIEF EXPLANATION ON PET CT

1. LYMPHOMAS- GIT
DR.ARIFKHAN S

2. GI LYMPHOMA
CLASSIFICATION SYSTTEMS
PET CT

3. Introduction
 GI lymphoma is uncommon;
 Extraa nodal involvement GI is more common; other site include spleen
,thymus to brain, soft tissue
 Non Hodgkin’s type almost exclusively
 Primary gastrointestinal involvement : the stomach
 can involve any part of the gastrointestinal tract from the esophagus to the
rectum.
 1.9 in 100000, a male-female ratio of 3:2.

4. Risk Factors
 HIV infection
 Helicobacter pylori infection,
 immunosuppression after solid organ transplantation,
 Celiac disease,
 inflammatory bowel disease
 human immunodeficiency virus infection.

5. Criteria for diagnosing primary
Extranodal lymphoma
 1. No palpable superficial lymph nodes are seen.
 2. Chest radiographic findings are normal (ie, no adenopathy).
 3. The white blood cell count (both total and differential) is normal.
 4. At laparotomy, the alimentary lesion is predominantly involved, with lymph node involvement
(if any) confined to the drainage area of the involved segment of gut.
 5. There is no involvement of the liver and spleen.

6. Frequency of GI occurrence by site
(of all lymphomas)
 Stomach
 Small intestine
 Rectum
 Rest of colon

7. Role of imaging
 Most common modality is CT , helps in assessing the stage of disease
 a wide variety of imaging appearances and definitive diagnosis relies on histopathologic
analysis,
Pointers in Imaging
 a bulky mass or diffuse infiltration
 with preservation of fat planes and
 no obstruction,
 multiple site involvement,
 associated bulky lymphadenopathy.

8.  Imaging also plays an important role in the detection of complications
such as perforation, obstruction, and fistulisation.
 However, advanced lymphomas arising in the gastrointestinal
tract may eventually disseminate widely and be clinically,
radiologically, and pathologically indistinguishable from
secondary gastrointestinal lymphomas

9. Staging
 stage I, tumor confined togastrointestinal tract, single primary site, and multiple
noncontiguous lesions.
 stage II, tumor extends into the abdominal cavity from the primary gastrointestinal site.
 (II1, local nodal involvement;
 II2, distant nodal involvement.
 Stage III, penetration through serosa to involve adjacent organs or tissues; and
 stage IV, disseminated extranodal involvement or a gastro-intestinal tract

10. Esophageal Lymphoma
 Secondary to cervical and mediastinal lymph node
 Contiguous spread from gastric lymphoma.
 Primary lymphoma of the esophagus is a rare condition.
 Primary esophageal lymphomas are predominantly B-cell type, (recent reports
diagnosing MALT lymphomas)
RADIOLOGICAL FEATURES
 Submucosal infiltration or polypoid mass.
 With ulceration or nodularity
 Barium studies  subtle mucosal and submucosal abnormalities.
 CT better defines the extent of local disease and the disease stage
Perforation and fistulisation can also be sen in CT and barium studies.

12. Gastric lymphoma
 Comprises 3-5% of all gastric neoplasms
 • Non-Hodgkin’s accounts for 80% of all gastric lymphomas
 • Begins in the submucosa
 • Most occur in distal body and antrum of stomach
 • Almost all gastric lymphoma presents with some degree of ulceration

13. Pathology
 Three distinct types of gastric lymphoma
 low-grade MALT lymphoma: 60% of all primary gastric lymphomas
 primary sporadic lymphoma: vast majority are B-cell non-Hodgkins lymphoma
 secondary involvement of the stomach by systemic lymphoma (usually high grade)
 Chronic H pylori gastritis is associated with the development of low-grade MALT Lymphoma,
having been reported to account for 50%–72% of all primary gastric Lymphomas.
 MALT lymphoma is treatable and has better prognosis in early stages.

14.  Nodular—single or multiple intragastric masses, easily confused with Ca
, protrude into the lumen, often with multiple ulcerations
 Polypoid—barium in interstices, frequently with ulceration; sometimes resembles metastatic
disease such as melanoma
 Ulcerative—shallow, saucer-like ulcer indistinguishable from Ca
 Infiltrative—thickened, irregular folds, simulating the appearance of hypertrophic gastritis; about
10% present this way

15.  Radiographic features
Fluoroscopy: barium meal
 Appearances vary from normal, to grossly abnormal.
 bull's eye appearance due to central ulceration.
 filling defects
 thickened gastric rugae
 linitis plastica

16.  CT
marked thickening of the stomach wall (2-4cm)
extensive lateral extension of the tumour (i.e. along the wall of the stomach) representing submucosal
spread .
submucosal spread encompasses the majority of the stomach, giving it a linitis plastica appearance.
uncommon for lymphoma to result in gastric outlet obstruction.
Rarely cause perigastric fat invasion.
homogeneous in attenuation, but may contain focal areas of low density representing necrosis.
Extensive retroperitoneal and local nodal enlargement.
 Complications such as obstruction, perforation, or fistulisation can occur as a result of the disease
itself or of treatment and can be detected with CT and barium studies

20. Differential diagnosis
gastric carcinoma
 more likely to cause gastric outlet obstruction
 more likely to be in the distal stomach
 more likely to extend beyond the serosa and obliterate adjacent fat plane
 more focal
 lymph nodes tend to be smaller and more localized to immediate draining nodes
gastrointestinal stromal tumour (GIST)
For diffuse gastric wall thickening also consider:
 gastritis
 Menetrier's disease: has a rugal like pattern.

21. Small Bowel lymphoma
 most common malignancy of the small bowel. ( 17-30% of all )
 related to B-cell hyperactivation in HIV positive patients.
 The distal ileum is classically thought to be the most common site.
 A circumferential bulky mass in the intestinal wall
 Predisposing conditions
AIDS
coeliac disease
organ transplant ( post transplant lymphoproliferative disorder (PTLD)
Helicobacter pylori positive patients
 Can present clinically as Gi haemorrhage , perforation, obstruction.

22. TYPES
 The type of lymphoma depends on the underlying predisposing condition.
H pylori: mucosa-associated lymphoid tissue lymphoma (MALToma)
PTLD: polyclonal B-cell non-Hodgkin's lymphoma (EBV associated)
HIV: B-cell non-Hodgkin's lymphoma 3 ,overall most common type.
T-cell lymphomas are seen but are uncommon 5, they have more perforation.

23.  Infiltrating form:
the most common type
focal or diffuse thickening of the bowel wall with
alternating areas of dilatation or constriction of
the bowel lumen
Folds in the affected segment are thickened,
nodular, effaced and may show ulceration

24.  Endoexoenteric form:
shows irregular collection of barium due to central
ulceration, associated with displacement of adjacent
bowel loops.
Associated mesentericabscess or fistula between the
tumor and adjacent bowel loops.

25.  Multiple nodular pattern: It is usually seen in T-cell
lymphoma complicating celiac disease and is considered most infrequent
 Polypoid form:
It causes submucosal filling defect and is often associated with intussusception

26. IMAGING
Typically involves a small segment (5-20cm).
Bowell wall thickening (1-7cm).
Aneurysmal dilatation: 30%, it occurs due to replacement of muscularis by tumor or infiltration of
myenteric nerve plexus.

27. Luminal narrowing is seen but obstruction is rare,

30. Peritoneal lymphomatosis from primary gastrointestinal lymphoma is rare.
When involved indistinguishable from carcinomatosis.

31. Large bowel lymphoma
 0.4% of all tumors of the colon,
 Colorectal lymphomas constitute 6%–12% of gastrointestinal lymphomas.
 Primary lymphoma more often affects the cecum and rectum.
 Most colorectal lymphomas are non- Hodgkin lymphomas, usually of B-cell origin.
 Mantle cell lymphoma is an aggressive disease that manifests as multiple polyps (lymphomatous
polyposis)
 Polyposis may also assosciated with MALT lymphoma.

32. IMAGING
Multiple polyps ; mostly near IC valve.
a diffuse or a focal segmental lesion with extensive mucosal ulceration at double-contrast barium enema
examination
Colonic perforation (T-cell lymphoma)
.
Circumferential thickening. (with or without ulceration)
a cavitary mass excavating into the mesentery;
Intussusception may occur with cecal involvement
Focal strictures, aneurysmal dilatation, ulcerative forms with fistula formation may be seen

35.  Primary rectal lymphoma is a rare type of gastrointestinal lymphoma and is clinically
indistinguishable from rectal carcinoma

36. MESENTRIC LYMPHOMA
 The most common malignant neoplasm affecting the mesentery.
Patterns of mesenteric lymphoma at CT
 multiple homogeneous masses encasing the mesenteric vessels “sandwich sign”.
 large “cakelike,” mass with low-attenuation areas of necrosis displacing small bowel loops.
 ill-defined infiltration of mesenteric fat, particularly after successful chemotherapy.
 bulky retroperitoneal adenopathy.
 ALWAYS ASSOSCIATED WITH SMALL BOWELL INVIOLVEMENT

37. v

38. Ann Arbor Staging of Extranodal
Lymphoma (Modified)
 IE Lymphoma restricted to GI tract on one side of diaphragm
IE1 Infiltration limited to mucosa and submucosa
IE2 Infiltration extending beyond submucosa
 IIE Lymphoma infiltrating lymph nodes on same sideof diaphragm
IIE1 Infiltration of regional lymph nodes
IIE2 Infiltration of lymph nodes beyond regional nodes
 IIIE Lymphoma infiltrating GIT and/ or lymph nodeson both sides of diaphragm
 IV Diffuse or disseminated involvement of liver, spleen, lung, brain

39. LUGANO CLASSIFICATION
radiological
 Stage I—Tumor confined to GI tract, single primary site or multiple noncontiguous lesions.
 Stage II—Tumor extends into the abdominal cavity fromthe primary GI site.
I1—Local nodal involvement
II2—Distant nodal involvement.
 Stage III—Penetration through serosa to involve adjacent organs or tissues.
 Stage IV—Disseminated extranodal involvement or a GI tract lesion with supradiaphragmatic
nodal involvement

40. Lymphoma Variants
 Burkitt’s Lymphoma
tumor of B lymphocytes seen
younger patients of less than 30 years of age. Ileocecal region is most frequently involved.
Large rapidly growing masses with mesenteric lymphadenopathy may be encountered
 Mediterranean Lymphoma
Mediterranean lymphoma affects younger persons.
There is marked thickening of the mucosal folds with nodules due to massive infiltration by plasma
cells
The unaffected intestinal loops show features of malabsorption in the form of flocculation,
segmentation and dilatation

41.  Multiple Lymphomatous Polyposis
a rare form of lymphoma
multiple polypoid lesions of malignant lymphoma are distributed throughout the GI
tract

42. FDG PET

43. INTRODUCTION
 extranodal disease
 The prevalence of extranodal involvement in non-Hodgkin lymphoma and Hodgkin disease
has increased in the past decade.
 subtle or absent at conventional computed tomography.
 Imaging of tumor metabolism is .the key to diagnose these sites
 2-[fluorine-18]fluoro-2-deoxy-d-glucose (FDG) positron emission tomography (PET) scan.

44. Uses
 To identify the involved sites.
 To distinguish between lesions (primary and relapse)
 Intiial staging (95% sensitivity on ombining with CT as in PET-CT)
 Follow up and Treatment response assessment.

46. Current revised response criteria
Indication of PET CT
 PET is routinely recommended for the staging of patients with FDG-avid, potentially curable
lymphomas
 PET is not routinely recommended prior to treatment for incurable, non-FDG-avid or indolent
histologic subtypes
 Midtreatment PET should be performed only as a part of clinical trials.

47. Principle
 3-dimensional, metabolic imaging technique that uses a radiopharmaceutical to target a specific
physiologic process.
 FDG is transported into cells and phosphorylated in a similar manner to glucose
 FDG-6-phosphate is not a substrate for glucose-6-phosphate isomerase and because FDG-6-
phosphate is typically not dephosphorylated in tumors
becomes trapped in the cell and reaches a near equilibrium state at approximately 60 minutes after
injection.
 The positron-emitting 18F isotope to which FDG is linked decays, and the emitted positron
annihilates after “bumping” into an electron, generating 2 511-KeV photons emitted in nearly
opposite directions that are detected by the PET scanner.

48.  defining positive PET findings as focal or diffuse FDG uptake above the surrounding
background in a location incompatible with normal anatomy/physiology.
 the standardized uptake value (SUV), representing the ratio of the tumoral tracer concentration
to the average tracer concentration in the entire body
 Radiopharmaceuticals:

49. Equipment
 PET/CT combines a full-ring detector PET scanner with a multidetector helical
 the PET scan is acquired immediately after the CT scan.
 The images are fused to provide precise localization of abnormal lesions.
 PET/CT provides more sensitive and specific imaging than either modality alone,
 Radiopharmaceuticals
Radiioisotope (F18, C11, Ga 67, I123, ) linked to a Metabolic substrate or Gas .

50. FDG uptake in NHL

52. Pitfalls of PET
Caution must be exercised in the interpretation of PET scans.
 technical limitations,
 variability of FDG avidity among the different lymphoma histologic subtypes
 In the large number of etiologies of false-negative and false-positive results
False positives arise because FDG is taken up in any process associated with increased glycolysis, for
example, inflammation, infection, granulomatous disease such as sarcoidosis, and brown fat
False-negative PET scans may result from lesions below the resolution of the scanner, generally 5 to 10
mm.

53. Conclusion
 Uncommon disease .
 a bulky mass or diffuse infiltration
 preservation of fat planes
 no obstruction,
 multiple site involvement,
 associated bulky lymphadenopathy
 CT is the most useful modality in that it provides a better overall assessment of the
disease stage.
 FDG-PET is now considered as a gold standard in pre and post therapeutic
evaluation of LYMPHOMas in general.

54. Thank you