Somatostatin-receptor scintigraphy for staging and follow-up of patients with extraintestinal marginal zone B-cell lymphoma of the mucosa associated lymphoid tissue (MALT)-type

Comprehensive Assessment of Somatostatin Receptors in Various Neoplasms: A Systematic Review

Somatostatin receptors (SSTR) are expressed in various neoplasms and can be targeted for both diagnostics as well as therapeutics. This systematic review aims to compile and discuss the prevalence of somatostatin receptor expression in various neoplasms. We performed a literature search from Google Scholar and PubMed using relevant keywords to look for all publicly available data regarding SSTR expression in various cancers. Both histopathological and radiographical studies were included for SSTR assessment. We found that many cancers express SSTR with varying prevalence. SSTR is now a well-established theranostics biomarker. We now have highly sensitive and specific diagnostic modalities like gallium 68 DOTATATE and copper 64 DOTATATE scans to screen for SSTR-2 and then target it therapeutically with lutetium 177 DOTATATE. A thorough understanding of SSTR expression in other tumors will open the channels for exploring potential SSTR targeting.

A case of primary hepatic extranodal marginal zone B-cell mucosa-associated lymphoid tissue (MALT) lymphoma treated by radiofrequency ablation (RFA), and a literature review

Primary hepatic mucosa-associated lymphoid tissue (MALT) lymphoma is an extremely rare liver malignancy that usually lacks characteristic imaging findings and which is often misdiagnosed. We report a 63-year-old woman diagnosed with primary hepatic extranodal marginal zone B-cell lymphoma, MALT type. The patient underwent needle biopsy and radiofrequency ablation (RFA), and showed no signs of relapse during the 12-month postoperative follow-up. This case stresses the rarity of primary hepatic MALT-type lymphoma and the unique and effective treatment for this patient. Our patient received RFA, which showed good efficacy and which provides a new option for the treatment of hepatic MALT lymphoma. We also present our findings from a systematic review to improve the current understanding of this disease.

Primary pancreatic lymphoma camouflaged under the umbrella of spectrum of neuroendocrine tumors in somatostatin receptor imaging

Primary pancreatic lymphomas are very rare as compared to other pancreatic neoplasms. However, unlike carcinomas, pancreatic lymphoma is treatable with satisfactory cure rates. Somatostatin receptor (SSTR) positron emission tomography/computed tomography (PET/CT) with ⁶⁸Ga-DOTANOC is a well-established diagnostic modality in the management of neuroendocrine tumors (NETs). Over the years, it has been evident that any neoplasm with SSTR expression shows increased tracer uptake, lymphoma, being the most prominent one. Herein, we report a case of pancreatic mass, suggested as NET on fine-needle aspiration cytology referred to us for staging. Whole-body ⁶⁸Ga-DOTANOC PET/CT scan showed a large pancreatic mass with peripancreatic nodes, level I cervical nodes, cardiac, and left testicular masses which were initially thought to be possibly metastatic from pancreatic NET. However, immunohistochemistry (IHC) of the specimen was suggestive of B-cell Non-Hodgkin's Lymphoma. The present case emphasizes that pancreatic lymphoma is one of the potential differentials for pancreatic masses apart from NET on SSTR imaging. Noteworthy is the fact, that IHC plays a poignant role in the evaluation and is a mandatory tool for the management of tumors. Moreover, the whole imaging picture and clinical scenario ought to be given utmost importance for giving an affirmative diagnosis on imaging. SSTR expression in lymphomas may further obviate a remote fact that peptide receptor radionuclide therapy can be considered as an end of the line treatment for refractory lymphomas.

Orbital lymphoma

Orbital lymphomas constitute 50-60% of ocular adnexal lymphomas. A total of 2211 cases of orbital lymphoma with a known subtype have been reported in the last 24 years (1994-2017). The vast majority of orbital lymphomas are of B-cell origin (97%), of which extranodal marginal zone B-cell lymphoma (EMZL) (59%) is the most common subtype, followed by diffuse large B-cell lymphoma (23%), follicular lymphoma (9%), and mantle cell lymphoma (5%). Orbital lymphoma is primarily a disease of the elderly. Gender distribution varies according to lymphoma subtype. However, extranodal marginal zone B-cell lymphoma (53%) and follicular lymphoma (75%) show a female predominance, whereas diffuse large B-cell lymphoma shows an even gender distribution. Mantle cell lymphoma has a striking male predominance of 80%. The histopathological subtype and the clinical stage of the disease are the best indicators of prognosis and patient outcome. Low-grade lymphomas such as extranodal marginal zone B-cell lymphoma and FL have a good prognosis, whereas high-grade lymphomas (diffuse large B-cell lymphoma and mantle cell lymphoma) are associated with a poor prognosis. When managing solitary low-grade lymphomas, radiotherapy is the treatment of choice. Chemotherapy, with or without radiotherapy, should be chosen for disseminated and high-grade lymphomas.

Expression of somatostatin and its receptor 1-5 in endometriotic tissues and cells

The present study aimed to detect the expression of somatostatin (SS) and SS receptor (SSTR)1-5 in tissues from patients with endometriosis (EMS). Reverse transcription-quantitative polymerase chain reaction analysis was applied to examine the expression of somatostatin gene in ectopic endometrial cells (EECs). The expression of somatostatin receptor 1–5 in the ectopic endometrium (EE), eutopic endometrium and normal endometrium and their association with EMS staging were determined by immunohistochemistry. The results indicated that the expression of SS in EECs was significantly higher compared with that in the control group. SSTR1-5 were expressed in the EE tissues from 30 patients with EMS, and the positive rates were 43.3, 70.0, 53.3, 50.0 and 96.7%, respectively, which were closely associated with EMS staging of the patients. The positive rates of SSTR1-5 expression in the eutopic endometrium from 12 patients with EMS were 33.3, 41.7, 58.3, 58.3 and 83.3%, respectively, while the positive rates of SSTR1-5 expression in the normal endometrium from 14 women without EMS were 7.1, 7.1, 21.4, 28.6 and 64.3%, which were lower than the positive rates of SSTR1-5 in the EE (43.3, 70, 53.3, 50 and 96.7%) and eutopic endometrial cells (33.3, 41.7, 58.3, 58.3 and 83.3%). In conclusion, SS was highly expressed in EECs. SSTR1-5 were expressed in the ectopic as well as eutopic endometrium, and low or moderate expression of SSTR1-4 and high expression of SSTR5 were detected in the ectopic and eutopic endometrial tissues, while low expression of SSTR1-4 and partial expression of SSTR5 were detected in normal endometrium. The positive rates of expression of SSTR1-5 in the EE cells and eutopic endometrium were higher than those in the normal endometrium. The expression of all the subtypes of SSTR in the EE tissues was closely associated with EMS staging.

The role of G protein-coupled receptors in lymphoid malignancies

B cell lymphoma consists of multiple individual diseases arising throughout the lifespan of B cell development. From pro-B cells in the bone marrow, through circulating mature memory B cells, each stage of B cell development is prone to oncogenic mutation and transformation, which can lead to a corresponding lymphoma. Therapies designed against individual types of lymphoma often target features that differ between malignant cells and the corresponding normal cells from which they arise. These genetic changes between tumor and normal cells can include oncogene activation, tumor suppressor gene repression and modified cell surface receptor expression. G protein-coupled receptors (GPCRs) are an important class of cell surface receptors that represent an ideal target for lymphoma therapeutics. GPCRs bind a wide range of ligands to relay extracellular signals through G protein-mediated signaling cascades. Each lymphoma subgroup expresses a unique pattern of GPCRs and efforts are underway to fully characterize these patterns at the genetic level. Aberrations such as overexpression, deletion and mutation of GPCRs have been characterized as having causative roles in lymphoma and such studies describing GPCRs in B cell lymphomas are summarized here.

Differential somatostatin and CXCR4 chemokine receptor expression in MALT-type lymphoma of gastric and extragastric origin

PURPOSE

Whereas the different somatostatin receptor (SSTR) subtypes and the chemokine receptor CXCR4 are known to be expressed in a wide variety of human malignancies, comprehensive data are still lacking for MALT-type lymphomas.

METHODS

Overall, 55 cases of MALT-type lymphoma of both gastric and extragastric origin were evaluated for the SSTR subtype and CXCR4 expression by means of immunohistochemistry using novel monoclonal rabbit antibodies. The stainings were rated by means of the immunoreactive score and correlated with clinical data.

RESULTS

While the CXCR4 was detected in 92 % of the cases investigated, the SSTR subtypes were much less frequently present. The SSTR5 was expressed in about 50 % of the cases, followed by the SSTR3, the SSTR2A, the SSTR4 and the SSTR1, which were present in 35, 27, 18 or 2 %, respectively, of the tumors only. Gastric lymphomas displayed a significantly higher SSTR3, SSTR4 and SSTR5 expression than extragastric tumors. A correlation between CXCR4 and Ki-67 expression was seen in gastric lymphomas, whereas primarily in extragastric tumors SSTR5 negativity was associated with poor patient outcome.

CONCLUSIONS

The CXCR4 may serve as a promising target for diagnostics and therapy of MALT-type lymphomas, while the SSTRs appear not suitable in this respect.

Primary hepatic mucosa-associated lymphoid tissue lymphoma: a case report and literature review

Primary hepatic mucosa-associated lymphoid tissue (MALT) lymphoma is an extremely rare disease. We herein describe the findings in a 74-year-old man with elevated liver enzyme levels. Dynamic computed tomography showed focal biliary dilation and atrophy in the posterior segment, while dynamic magnetic resonance images revealed a small, highly enhanced small mass located at the root of posterior branch of the biliary ducts. As the mass was not detected on abdominal ultrasonography, a biopsy could not be performed. Cholangiocellular carcinoma was suspected, and surgery was performed. However, the surgically resected hepatic tumor was a nodule of aggregated lymphocytes that formed a lymphoepithelial lesion. Immunohistochemical analysis revealed that the lymphoma cells were positive for CD20 and CD79a, but negative for CD3. No other lymphoid lesions were found during additional postoperative examinations. Therefore, the patient was diagnosed with primary hepatic MALT lymphoma. He was also diagnosed with Helicobacter pylori infection, and thus, pylorus eradication was performed. At the time of this report, the patient was free of disease for 2 years without any additional treatment. The present case contributed to the diagnosis and management of this rare disease, as previously published case reports described varying imaging features; it also suggested that preoperative diagnosis was often difficult without biopsy.

Managing lymphoma with non-FDG radiotracers: current clinical and preclinical applications

Nuclear medicine imaging modalities such as positron emission tomography (PET) and single-photon emission computed tomography (SPECT) have played a prominent role in lymphoma management. PET with [(18)F]Fluoro-2-deoxy-D-glucose (FDG) is the most commonly used tool for lymphoma imaging. However, FDG-PET has several limitations that give the false positive or false negative diagnosis of lymphoma. Therefore, development of new radiotracers with higher sensitivity, specificity, and different uptake mechanism is in great demand in the management of lymphoma. This paper reviews non-FDG radiopharmaceuticals that have been applied for PET and SPECT imaging in patients with different types of lymphoma, with attention to diagnosis, staging, therapy response assessment, and surveillance for disease relapse. In addition, we introduce three radiolabeled anti-CD20 antibodies for radioimmunotherapy, which is another important arm for lymphoma treatment and management. Finally, the relatively promising radiotracers that are currently under preclinical development are also discussed in this paper.

Technetium-99m depreotide imaging by single photon emission tomography/low resolution computed tomography in malignant lymphomas: comparison with gallium-67 citrate

OBJECTIVE

Previous studies have demonstrated the feasibility of targeting lymphoma lesions with somatostatin receptor binding agents, mainly with In-111-pentetreotide. In the present work another somatostatin analog, Tc-99m depreotide, is investigated.

METHODS

One-hundred and six patients, 47 with Hodgkin's (HL) and 59 with various types of non-Hodgkin's lymphoma (NHL), were imaged with both Tc-99m depreotide and Ga-67 citrate. Planar whole-body and single photon emission tomography/low resolution computerized tomography (SPECT/CT) images were obtained. A total of 142 examinations were undertaken at different phases of the disease. Depreotide and gallium findings were compared visually and semi-quantitatively, with reference to the results of conventional work-up and the patients' follow-up data.

RESULTS

In most HL, intermediate- and low-grade B-cell, as well as in T-cell NHL, depreotide depicted more lesions than Ga-67 and/or exhibited higher tumor uptake. The opposite was true in aggressive B-cell NHL. However, there were notable exceptions in all lymphoma subtypes. During initial staging, 93.3% of affected lymph nodes above the diaphragm, 100% of inguinal nodes and all cases with splenic infiltration were detected by depreotide. On the basis of depreotide findings, 32% of patients with early-stage HL were upstaged. However, advanced HL and NHL cases were frequently downstaged, due to low sensitivity for abdominal lymph node (22.7%), liver (45.5%) and bone marrow involvement (36.4%). Post-therapy, depreotide detected 94.7% of cases with refractory disease or recurrence. Its overall specificity was moderate (57.1%). Rebound thymic hyperplasia, various inflammatory processes and sites of unspecific uptake were the commonest causes of false positive findings. The combination of depreotide and gallium enhanced sensitivity (100%), while various false positive results of either agent could be avoided.

CONCLUSION

Except perhaps for early-stage HL, Tc-99m depreotide as a stand-alone imaging modality has limited value for the initial staging of lymphomas. Post-therapy, however, depreotide scintigraphy seems useful in the evaluation of certain anatomic areas, particularly in non-aggressive lymphoma types. The combination with Ga-67 potentially enhances sensitivity and specificity. If fluorodeoxyglucose positron emission tomography is not available or in case of certain indolent lymphoma types, Tc-99m depreotide may have a role as an adjunct to conventional imaging procedures.

Extranodal marginal zone lymphoma of the ocular adnexa

Lymphomas of the ocular adnexa are a heterogeneous group of malignancies, composing approximately 1% to 2% of non-Hodgkin lymphomas (NHLs) and 8% of extranodal lymphomas. The most common subtype, accounting for up to 80% of cases of primary ocular adnexal lymphoma, is marginal zone lymphoma of mucosa-associated lymphoid tissue (MALT) type. In the recent past, there have been significant advances in our understanding of the clinical characteristics, morphology and phenotype, etiology, pathogenesis, diagnosis, natural history, treatment approaches, outcome, and prognostic factors of this disease entity. Novel immunologic and molecular techniques have aided in the distinction between MALT lymphoma and other lymphoproliferative disorders and led to the identification of tissue markers of prognostic significance. Modern imaging modalities provide invaluable tools for accurate staging and treatment planning. Besides radiotherapy and chemotherapy, a variety of new treatment options have emerged in the management of patients with ocular adnexal MALT lymphoma, especially monoclonal antibody therapy and antibiotic therapy against Chlamydia psittaci, which has been associated with the pathogenesis of ocular adnexal lymphomas in some parts of the world. In this review, we present a state-of-the-art summary of ocular adnexal MALT lymphomas.

Primary hepatic marginal zone B cell lymphoma of mucosa-associated lymphoid tissue type: case report and review of the literature

A primary hepatic marginal zone B cell lymphoma of mucosa-associated lymphoid tissue (MALT) is very rare. We found a solitary mass 27 mm in size in the left lobe of the liver of a 58-year-old Japanese man with a history of hepatitis-C infection. Based on the results of imaging studies, the tumor was diagnosed as a hepatocellular carcinoma (HCC). The left lobe of the liver was lobectomized and microscopic findings showed that the tumor was a hepatic MALT lymphoma, while immunohistochemistry showed it to be positive for CD20 and CD79a. In a fluorodeoxyglucose-positron emission tomography examination integrated with computed tomography scanning (FDG-PET CT) before surgery, the tumor was revealed to have a high standardized uptake value (SUV) for FDG. The patient received chemotherapy after surgery. To the best of our knowledge, 45 cases had been reported with a mean age for all patients of 61.4 years. The pathogenesis remains unclear, although half of the patients had a past history of chronic inflammatory liver disease. Surgical resection was performed in most cases and some patients received postoperative chemotherapy or radiotherapy. The clinicopathologic characteristics and management of this extremely rare disease are also discussed.

Primary hepatic lymphoma of mucosa-associated lymphoid tissue type: a case report with cytogenetic study

Primary hepatic lymphoma of mucosa-associated lymphoid tissue type is extremely rare. Only 38 cases have been reported to date. A case of a 59-year-old man with Helicobacter pylori-resistant gastric ulcers and Buerger disease who was followed up since 1999 is reported. A 2-cm hepatic nodule was incidentally found during partial gastrectomy and corresponded to mucosa-associated lymphoid tissue-type lymphoma without underlying liver disease. Molecular studies showed a clonal immunoglobulin heavy-chain gene rearrangement. Investigations for the mucosa-associated lymphoid tissue lymphoma-associated translocations t(11;18) and t(14;18), as well as the t(3;14)(q27;q32), were negative, whereas trisomy 3 and trisomy 18 were detected.

Somatostatin receptor scintigraphy with 111In-DOTA-lanreotide and 111In-DOTA-Tyr3-octreotide in patients with stage IV melanoma: in-vitro and in-vivo results

The overexpression of somatostatin receptors (SST-Rs) on various tumour cells provides the molecular basis for the successful use of radiolabelled SST analogues in clinical oncology. The objective of the study was to evaluate the tumour binding of In-1,4,7,10-tetraazacyclo-dodecane-N,N',N'',N'''-tetraacetic acid-lanreotide (In-DOTA-LAN) and In-DOTA-tyrosine-octreotide (In-DOTA-Tyr-OCT) in patients with stage IV melanoma. In addition, we evaluated the potential antiproliferative effect of SST analogues, together with an assessment of the functionality of SST-Rs, on four melanoma cell lines. Twenty-three patients with advanced metastatic melanoma underwent scintigraphy. Thirty-eight of 61 lesions (62%) were positively imaged with In-DOTA-LAN, whereas 23 (37%) were negative. With In-DOTA-Tyr-OCT, 10 of the 23 documented lesions (43%) were positive and 13 (56%) were negative. In vitro, cell lines showed no growth inhibition in the presence of SST analogues and no influence on cell cycle distribution was found with the addition of SST analogues to cultured cells. In addition, no functional surface SST-Rs could be demonstrated on these cell lines. Taken together, our results demonstrate the visualization of metastatic melanoma in a high percentage of patients, probably due to binding of SST analogues to SST-Rs on tumour vessels or infiltrating immune cells. Judging from our data, however, there is no evidence of functional SST-R expression on melanoma cells.

Initial Staging of Lymphoma With Octreotide and Other Receptor Imaging Agents

Somatostatin receptor scintigraphy is useful in diagnosing tumors with increased expression of somatostatin receptors. The correct use of this technique reveals the localization of neuroendocrine primary tumors and unknown metastases in approximately 90% of patients. However, somatostatin receptor scintigraphy also can image many other human tumors expressing somatostatin receptors, including malignant lymphomas and thymomas. The sensitivity of somatostatin receptor scintigraphy to image somatostatin receptor-positive tumors is very high, but due to the variable expression of specific receptor subtypes, the specificity can be relatively low. This drawback is crucial in evaluating lymphoproliferative diseases, or, in general, when immune cells are involved. The sensitivity of somatostatin receptor scintigraphy for Hodgkin's lymphoma is 95%-100%, whereas for non-Hodgkin's lymphoma it is around 80%. It has been shown that the uptake of [(111)In-DTPA(0)]octreotide in lymphomas is lower compared to the uptake in neuroendocrine tumors. This is mainly attributed to the low number of receptors on immune cells compared to neuroendocrine cells; however, ligand-induced internalization and differential receptor regulation may also participate in determining this phenomenon. Therefore, caution should be taken when interpreting data from some studies. Several new ligands are currently under study to improve these limits and the expression of other neuropeptide receptors is being investigated to provide a molecular basis for in vivo multireceptor targeting of tumors. With the use of currently available somatostatin analogs, somatostatin receptor scintigraphy does not seem to have a significant impact in patients with lymphomas for diagnostic purposes. There are a few exceptions, however. Among these, the staging and restaging of extragastric lymphoma MALT-type may present some advantages. Conversely, somatostatin receptor scintigraphy in the imaging of thymic malignancies could enhance both our diagnostic and therapeutic capabilities. Somatostatin receptor scintigraphy is diagnostically relevant in differentiating malignant from benign lesions, especially in those patients with associated paraneoplastic syndromes, and is the main criterion to select patients suitable for therapy with somatostatin analogs. Recent findings emerging from in vitro studies on somatostatin receptor physiology in immune cells will certainly reopen and expand the potential applications of somatostatin analogs for in vivo diagnostic and therapeutic options.

Receptor-Mediated Tumor Targeting with Radiopeptides. Part 1. General Concepts and Methods: Applications to Somatostatin Receptor-Expressing Tumors

Radiolabeled peptides have become important tools in nuclear oncology, both as diagnostics and more recently also as therapeutics. They represent a distinct sector of the molecular targeting approach, which in many areas of therapy will implement the old "magic bullet" concept by specifically directing the therapeutic agent to the site of action. In this three-part review, we present a comprehensive overview of the literature on receptor-mediated tumor targeting with the different radiopeptides currently studied. Part I summarizes the general concepts and methods of targeting, the selection of radioisotopes, chelators, and the criteria of peptide ligand development. Then, the >400 studies on the application to somatostatin/somatostatin-release inhibiting factor receptor-mediated tumor localization and treatment will be reviewed, demonstrating that peptide radiopharmaceuticals have gained an important position in clinical medicine.

Somatostatin receptor scintigraphy in MALT lymphoma of the lacrimal gland treated with rituximab

Non-gastric stage I extranodal marginal zone lymphomas of MALT are usually treated with local therapy. However, distant relapses in other extranodal sites are not uncommon suggesting under-staging of these patients using conventional image studies. Positron emission tomography (PET) scans are frequently negative in this subgroup of patients with lymphoma and therefore do not significantly contribute to the staging process. We present a case of lacrimal gland MALT lymphoma demonstrating the usefulness of somatostatin receptor scintigraphy for initial staging and evaluation of response to treatment.

G and D cells in rat antral mucosa: An immunoelectron microscopic study

AIM: To investigate the gastrin secreting cells (G cells) and the somatostatin secreting cells (D cells) of antral mucosa in rats at the ultrastructural level.

METHODS: Revised immunoelectron microscopic technique was used to detect the G cells and D cells in rat antral mucosa through gastrin and somatostatin antibodies labeled by colloidal gold. Also the relevant quantitative analysis regarding the granular number of colloidal gold in G cells and in D cells was conducted.

RESULTS: Immunological granules of colloidal gold were distributed in G cells and D cells. Gastrin labeled golden granules or somatostatin labeled ones presented mainly as lobation-like or island-like congeries. Most of the golden congeries were observed dissociated in cytoplasms of G cells or D cells, near the basement membrane. A few golden congeries were located in nuclei. The number of golden granules in one G cell was around 107.04 ± 19.68 and was 83.36 ± 17.58 in one D cell.

CONCLUSION: Gastrin secreting granules are located in cytoplasms and nuclei of G cells, and somatostatin secreting granules both in cytoplasms and in nuclei of D cells. The number of golden granules can be quantitatively analyzed to determine the relative amount of gastrin secreting granules or somatostatin secreting granules.

Extranodal lymphoma originating from mucosa-associated lymphoid tissue of the nasopharynx

Non-Hodgkin's lymphoma originating from mucosa-associated lymphoid tissue has been connected with autoimmune disease. These tumours often arise in gastric mucosa and are extremely rare in airway mucosa. Three cases of mucosa-associated lymphoid tissue lymphoma in the cavum have been reported in the literature. A 52-year-old male with rheumatoid arthritis presented with an 8-month history of nasal obstruction and recurrent nasal blood discharge. On physical examination a bulky mass was observed in the nasopharynx. CT demonstrated a soft tissue lesion in the nasopharynx without bone destruction. MRI showed a contrast-enhanced mass with extension to the left pterygoid muscle. Biopsy revealed a low-grade B-cell lymphoid tumour of the marginal zone. The patient received six cycles of cyclophosphamide, vincristine and prednisone with adriamycin treatment, together with intracranial methrotrexate as a prophylactic measure. After 48 months of follow-up there was no evidence of disease and a control MRI scan was normal. The prognosis of this type of tumour is unpredictable and there are too few cases to enable definitive conclusions to be drawn.

111In-DOTA- dPhe1-Tyr3-octreotide, 111In-DOTA-lanreotide and 67Ga citrate scintigraphy for visualisation of extranodal marginal zone B-cell lymphoma of the MALT type: a comparative study

Somatostatin receptor (SSTR) scintigraphy and gallium-67 citrate ((67)Ga) scintigraphy have been used for visualisation of Hodgkin's lymphoma and non-Hodgkin's lymphoma. However, experience with B-cell lymphoma of the mucosa-associated lymphoid tissue (MALT) type is very limited. The aim of this study was to prospectively compare the (67)Ga scintigraphy results with those obtained by (111)In-DOTA- dPhe(1)-Tyr(3)-octreotide ((111)In-DOTA-TOCT) and (111)In-DOTA-lanreotide ((111)In-DOTA-LAN) scintigraphy in patients with proven MALT-type lymphoma. Comparative scintigraphic examinations using (67)Ga, (111)In-DOTA-TOCT and (111)In-DOTA-LAN were performed in 18 patients (11 female and 7 male, median age 64+/-15 years) with histologically verified MALT-type lymphomas of various origin. Planar and single-photon emission tomography imaging acquisitions were performed after injection of a mean dose of 185+/-26 MBq (67)Ga and 165+/-20 MBq (111)In-DOTA-TOCT or (111)In-DOTA-LAN. All scintigraphic results were correlated with other conventional examinations including gastroscopy, colonoscopy, endosonoscopy, ophthalmologic investigation, CT of the thorax and abdomen and bone marrow biopsy. This comparative study showed that (67)Ga scintigraphy found abnormalities in 10 of 16 patients (63%) and detected 18 of 31 clinically involved sites (58%), but was false positive in three patients. (111)In-DOTA-TOCT found abnormalities in 9 of 15 patients (60%) and detected 15 of 27 clinical lesions (56%); it was false positive in two patients. (111)In-DOTA-LAN scintigraphy showed abnormalities in 7 of 11 patients (64%) and found 12 of 22 clinical lesions (55%). False-positive (111)In-DOTA-LAN scan results were found in two patients. For supra-diaphragmatic lesions, (67)Ga scintigraphy detected 12 of 16 sites (75%). (111)In-DOTA-TOCT scintigraphy revealed 7 of 15 lesions (47%). (111)In-DOTA-LAN showed 6 of 12 positive sites (50%). For infra-diaphragmatic involvement, the sensitivities of (67)Ga, (111)In-DOTA-TOCT and (111)In-DOTA-LAN were 40%, 67% and 60%, respectively. It is concluded that MALT-type lymphoma can be visualised by (67)Ga, (111)In-DOTA-TOCT and (111)In-DOTA-LAN scintigraphy. Although there were no statistically significant differences in patient-related and site-related sensitivities when using (67)Ga compared with (111)In-DOTA-TOCT and (111)In-DOTA-LAN, the sensitivity of (67)Ga tended to be superior to that of (111)In-DOTA-TOCT and (111)In-DOTA-LAN for supra-diaphragmatic lesions but inferior for infra-diaphragmatic involvement. In selected cases, the combination of (67)Ga and (111)In-DOTA-LAN or (111)In-DOTA-TOCT may increase the diagnostic efficiency in patients with MALT-type lymphoma.