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Findings: Gallium scan at 48 and 72 hours shows mediastinal adenopathy and bilateral breast uptake.

Diagnosis: Hodgkin's Lymphoma

Discussion: The patient's final diagnosis was Hodgkin's lymphoma. The breast uptake represents benign uptake secondary to lactation.

The mechanism of Gallium uptake remains controversial. In neoplastic diseases it has been shown to correlate with metabolic activity as well as histologic viability. In circulation, Gallium is protein bound, predominantly to transferrin. In normal tissues, Gallium localizes mainly to lysosomes. In tumors it is felt to localize to lysosome-like bodies. There is also a possibility that Gallium-transferrin complexes bind to a transferrin receptor in tumor cell membranes.

The normal distribution of Gallium is within liver, spleen, bone marrow and bone. There is also transient colonic accumulation. There are multiple conditions which can alter Gallium distribution. As this case illustrates, breast uptake can be seen in benign conditions such as lactation, pregnancy and the use of oral contraceptives. Other conditions include previous chemotherapy which can result in increased uptake in salivary glands, as well as diffusely increased pulmonary uptake. Prominent colonic uptake can be seen with the use of cathartics as well as in constipation. Therefore, in scan interpretation these pitfalls, to name a few, should be avoided.

Gallium was initially noted to localize in patient's with lymphoma. Subsequently, it was seen to localize in additional tumors and sites of inflammation. Its main utility in lymphoma is for staging. Prognosis in Hodgkin's disease (HD) and non- Hodgkin lymphoma (NHL), to a lesser extent, is dependent on stage. An initial pretherapy scan is obtained to determine if the patient's disease is Gallium avid. If so, the initial scan can be used for staging. The sensitivity of Gallium for HD is 93% and 89% for NHL with a specificity of 100%. Gallium scanning is subsequently used for restaging.

References:
Kaplan WD, Anderson KC, Leonard, RCF: High Dose Gallium Imaging
in the Evaluation of Lymphoma. 1983, J. Nucl Med 24:50.

McLaughlin AF, McGee MH, Grenau R, et al: Current Role of
Gallium Scanning in the Management of Lymphoma 1990 Eur J Nucl
Med 16:755-771.

Larson SM, Rasi JS, Allan RD, et al: Common Pathway for Tumor
Uptake of Gallium-67 and Iron-59 via a transferrin receptor.
1980 J Natl Cancer Inst. 64:51-53.

Hoffer PB: Mechanisms of Localization. In Hoffer PB, Beckerman
C, Henkin RE, Editors. Gallium-67 Imaging. 1978 John Wiley, New
York, Pages 4-8.

Murray IP, Ell PJ, Nuclear Medicine in Clinical Diagnosis and
Treatment. 1994: Churchill-Livingston.

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