CASE REPORT Annals of Nuclear Medicine Vol. 12, No. 1 51-53, 1998 Gallium-67-citrate scintigraphy of primary renal lymphoma Mitsuru TANIGUCHI, Koutarou HIGASHI, Manabu OHGUCHI, Tetsurou OKIMURA and Itaru YAMAMOTO Department of Radiology, Kanazawa Medical University We present a case of primary renal lymphoma, which is a rare entity and poses diagnostic challenge. Ultrasound and CT scan demonstrated a nonspecific solid tumor in the left kidney. 67Ga-citrate scintigraphy demonstrated an intense uptake in the tumor, which led to a correct diagnosis, so that we could spare unnecessary laparotomy and possible nephrectomy. Key words: kidney, neoplasms, lymphoma, gallium-67 imaging Received September 10, 1 997, revision accepted October 20, 1997. For reprint contact: Mitsuru Taniguchi, M.D., Department of Radiology, Kanazawa Medical University, Daigaku 1-1, Uchinada, Kahoku-gun, Ishikawa 92O-0293, JAPAN. E-mail: tngc @po2.nsknet.or.jp INTRODUCTION SECONDARY RENAL INVOLVEMENT from systemic lymphoma is a common occurrence, with previous reports demonstrating approximately a 50% incidence at autopsy;1 it occurs more commonly with non-Hodgkin lymphoma and less often with Hodgkin lymphoma.2 Primary renal lymphoma, with no evidence of involvement elsewhere, is extremely rare,3-6 since the kidney does not normally contain lymphoid tissue. Whether primary or secondary, early diagnosis and treatment are essential for a cure, but these may be difficult due to nonspecific findings on ultrasound or CT scan. In this report, we present our experience with 67Ga scintigraphy in a patient with primary renal lymphoma, and emphasize the contribution of 67Ga scintigraphy to the initial diagnosis of it. CASE REPORT A 79-year-old man was referred to the urology section for a several day history of left lumbago. There were no palpable adenopathies or tumors. Urinalysis revealed pH 5.0, 50 to 100 red blood cells per high power field, and abnormal cells (class V). Blood examination revealed mild anemia, and increase in LDH (794 IU/liter, normal: 180-460), BUN (22 mg/dl, normal: 8-20) and creatinine (1.7 mg/dl, normal: 0.6-1.2). An abdominal ultrasound demonstrated enlargement of the left kidney with a large, ill-defined, weakly echogenic tumor. On an abdominal CT scan, the lesion was demonstrated as an ill-defined, inhomogeneous, low-density tumor, infiltrating and replacing the renal parenchyma (Fig. 1). No discernible sites of lymphomatous lesion other than the kidney were demonstrated by ultrasound, CT scan, MR imaging and bone marrow aspiration. On an angiography, the left renal tumor was hypovascular. A 67Ga-citrate scintigraphy was performed 48 hours after the intravenous administration of 111 MBq of 67Ga-citrate. Whole body images were acquired on a large field-of-view gamma camera (SNC-510R, Shimadzu, Kyoto. Japan) with a medium energy collimator. A solitary area of intense uptake was demonstrated in the left kidney (Fig. 2). Subsequently we performed an ultrasound-guided percutaneous needle biopsy of the left renal tumor. The histological examination revealed non-Hodgkin lymphoma (B-cell, diffuse, large cell type) (Fig. 3). Although laparotomy with possible nephrectomy had been arranged by the urologists at first, it was omitted after the 67Ga scintigraphy and the biopsy, and the patient was then transferred to the section of hematology for chemotherapy. DISCUSSION There was once much debate as to whether primary renal lymphoma exists as a separate clinical entity, because of the absence of lymphoid tissue in the normal kidney, but a few well-documented cases can be found in the literature,3-6 and now it is commonly accepted that lymphoma can be primary in the kidney though extremely rare. Puente Duany N. has postulated that lymphoid cells are drawn to the kidney by a preexisting inflammatory process such as pyelonephritis and once they are there the untimely oncogenic event may take place.7 Recognition of renal lymphoma in the initial diagnosis of a renal tumor has obvious clinical importance because lymphoma and other tumors (such as renal cell carcinoma or transitional cell carcinoma) are treated very differently; the former is generally treated with chemotherapy or radiation, the latter with surgical resection as much as possible. The majority of renal tumors can be identified and characterized by both ultrasound and CT scan, but some lesions fail to meet the established criteria of the specific diagnosis; one of these "indeterminate" renal tumors is lymphoma.8 Secondary renal lymphoma has been documented as multiple nodules, invasion from retroperitoneal disease or a solitary tumor, whose predominant appearance on ultra-sound and CT scan is characteristic, but certainly nonspecific.9-ll In spite of this, secondary renal lymphoma is readily suggested and is not difficult to differentiate for the following reasons: firstly, the patient usually has histologically-proven lymphoma in another site or a history of the disease, secondly, it is often accompanied with retroperitoneal adenopathy or splenomegaly, thirdly, after chemotherapy it may resolve along with a lymphomatous lesion in another site. On the other hand, the diagnosis of primary renal lymphoma is quite difficult because of the absence of the abovementioned features. Most of the primary cases, as documented in our case, have been presented with a solitary solid renal tumor requiring exploration, and often undergone nephrectomy because of unawareness of lymphoma.3-5 67Ga-citrate scintigraphy has been proved to play an important role in the staging and the detection of recur-rence of lymphoma.12-15 As for the initial diagnosis of lymphoma, in general 67Ga has little role prior to biopsyl2,15 because 67Ga is not a specific agent for lymphoma and accumulates also in other tumors and inflamed tissues.15,16 But in our case the intense 67Ga uptake in the renal tumorled to consideration of lymphoma. The reasons are as follows: firstly, solid renal tumors other than lymphoma have scarcely accumulated 67Ga, except for metastatic melanoma,16,17 wherein, however, an accompanying primary skin lesion would have already been identified, secondly, the majority of inflammatory renal diseases, especially in the acute phase, would be suspected on the basis of history, urinalysis and blood examination. And both of the conditions were excluded in this case. In this case, we diagnosed renal lymphoma by means of the ultrasound-guided percutaneous needle biopsy and could avoid unnecessary laparotomy and possible nephrectomy. In general, whether a needle biopsy of a renal tumor is performed prior to laparotomy or not mostly depends on the preference of the referring physician. But a needle biopsy should be recommended by the radiologist to investigate the possibility of lymphoma when an indeterminate renal tumor reveals an intense 67Ga uptake. An additional advantage of 67Ga is the provision of total body information. Diagnostically, this is useful especially when the renal lesion presents as the earliest manifestation of systemic lymphoma both because one may detect widespread involvement of lymph nodes or other organs which arouses strong suspicion of lymphoma and because one may find another lesion which is less invasive or more suitable for needle biopsy than the kidney. In conclusion, it is worthwhile to perform 67Ga scintigraphy prior to biopsy or laparotomy to investigate the possibility of renal lymphoma when other imaging methods such as ultrasound and CT scan demonstrate a non-specific renal tumor. REFERENCES l. Richmond J, Sherman RS, Diamond HD, Craver LF. Renal lesions associated with malignant lymphomas. Am J Med 32: 184-207, 1962. 2. Hartman DS, Davis CJJ, Goldman SM, Friedman AC, Fritzsche P. Renal lymphoma: radiologic-pathologic corre-lation of 21 cases. Rediology 144: 759-766, 1982. 3. Knoepp LF. Lymphosarcoma of the kidney. Surgery 39: 510-514, 1956. 4. Silber SJ, Chang CY. Primary renal lymphoma of kidney. J Urol 11O: 282-284, 1973. 5. Kandel LB, McCullough DL. Harrison LH. Woodruff RD, Ahl ETJ. Munitz HA. Primary renal lymphoma. Does it exist? Cancer 60: 386-391, 1987. 6. Dobkin SF, Brem AS, Caldamone AA. Primary renal lymphoma. J Urol 146: 1588-1590, 1991. 7. Puente Duany N. Linfosarcoma y linfosarcomatosis de los rinones: part 2. Rev Med Trop Parasitol Bacteriol Clin Lab 6: 213, 1940. 8. Kawashima A, Goldman SM, Sandler CM. The indeterminate renal mass. Radiol Clin North Am 34: 997-1014, 1 996. 9. Eisenberg PJ, Papanicolaou N, Lee MJ, Yoder IC. Diagnostic imaging in the evaluation of renal lymphoma. Leuk Lymphoma 16: 37-50, 1994. 10. Glazer HS, Lee JKT, Balfe DM. Mauro MA. Griffith R, Sagel SS. Non-Hodgkin lymphoma: computed tomographic demonstration of unusual extranodal involvement. Rodiology 149: 211-217, 1983. 11. Heiken JP. Gold RP, Schnur MJ. King DL. Bashist B, Glazer HS. Computed tomography of renal lymphoma with ultrasound correlation. J Comp Assist Tomogr 7: 245-250, 1983. 12. Tumer DA, Fordham EW, Ali A. Slayton RE. Gallium-67 imaging in the management of Hodgkin's disease and other malignant lymphomas. Semin Nucl Med 8: 205-21 8, 1978. 13. Johnston GS, Go MF. Benua RS. Larson SM, Andrews GA, Hubner KF. Gallium-67 citrate imaging in Hodgkin's disease: final report of cooperative group. J Nucl Med 1 8: 692-698, 1977. 14. Andrews GA. Hubner KF. Greenlaw RH. Ga-67 citrate imaging in malignant lymphoma: final report of cooperative group. J Nucl Med 19: 1013-1019, 1978. 15. Hauser MF, Alderson PO. Gallium-67 imaging in abdominal disease. Semin Nucl Med 8: 251-270, 1978. 16. Frankel RS. Richman SD. Levenson SM. Johnston GS. Renal localization of gallium-67 citrate. Radilogy 114: 393-397, 1975. 17. Sauerbrunn BJL, Andrews GA. Hubner KF. Ga-67 citrate imaging in tumors of the genito-urinary tract: report of cooperative study. J Nucl Med 19: 470-475, 1978.