Different FDG uptake in extranodal marginal zone MALT lymphomas according to primary sites of lymphoma involvement

Objectives The usefulness of FDG-PET in extranodal marginal zone B cell lymphoma of mucosa-associated lymphoid tissue type(MALT) is controversial. This study assessed FDG avidity in various MALT lymphomas and investigated whether the sensitivity of FDG-PET/CT is different according to primary sites of MALT lymphoma.

Methods A total of 106 patients with biopsy proven MALT lymphoma, who underwent PET/CT before treatment from May-2004 to Apr-2008, were enrolled in this retrospective study. The primary sites of disease were stomach in 48, conjunctiva-eyelid in 33 and others in 25. FDG avidity(SUVmax & visual) and the sensitivity of FDG PET/CT according to disease site were assessed.

Results Of all 106 patients, only 33 (31.1%) patinets with MALT lymphomas showed FDG avid lesions on PET/CT images. The sensitivity for detecting MALT lymphoma lesions were significantly different according to primary sites of disease (20.8%(10/48) in stomach, 9.1%(3/33) in conjunctiva-eyelid and 80.0%(20/25) in others. P<0.05). H-pylori infection made different FDG uptake in gastric MALT lymphoma(sensitivity of H-pylori positive group is 13.5%(5/37) and sensitivity of H-pylori negative group is 45.5%(5/11), p<0.05). Detection rate of additional involvement or high grade transformation is 6.6% (7/106, 3 additional sites of involvement & 4 high grade transformation).

Conclusions The sensitivity of FDG-PET/CT in gastric & conjunctiva-eyelid MALT lymphomas was very low. In MALT lymphomas of other primary sites, it was higher than gastric & conjunctiva-eyelid MALT lymphomas. H-pylori infection could make a significant difference in FDG avidivity of gastric MALT lymphoma.