Introduction

Mantle cell lymphoma (MCL) accounts for approximately 5% of all lymphomas. MCL has a male and adult predominance. Generally it presents with disseminated disease, splenomegaly and bone marrow involvement. MCL tends to involve extranodal sites, and the most commonly involved extranodal sites are reported as gastrointestinal tract, Waldeyer’s ring, skin, and ocular adnexa. Testicular involvement of MCL is extremely rare. Few cases were reported in literature but Positron emission tomography/computed tomography (PET/CT) modality wasn’t used in any of them (1,2). To the best of our knowledge, this is the first case reporting testicular involvement of MCL by PET/CT.

Case Report

A 72 year-old-male was diagnosed with MCL. He received chemotherapy and underwent PET/CT three months later for subsequent evaluation. PET/CT showed marked progression of lymphomatous disease with extremely high metabolic activity on nodal, osseous and extranodal sites (Figure 1). There was hypermetabolism in the external iliac nodal conglomerate that measured approximately 3.0 cmx2.3 cm in size, with a maximum standardized uptake value (SUVmax) of 57.5 (Figure 2), as well as in the right inguinal nodal chain (Figure 3). In addition, there was evidence of extranodal disease with increased metabolic activity in bilateral testicles (Figure 3), bilateral adrenal glands, and several subcutaneous hypermetabolic soft tissue nodules. The largest subcutaneous soft tissue nodule was within the left buttock, and had a SUVmax of 12.2 (Figure 4). Within a month following PET/CT imaging, core biopsy was performed from the left buttock lesion. Pathology report confirmed the diagnosis of MCL with a pleomorphic variant.

Literature Review and Discussion

MCL is an aggressive sub-type of non-Hodgkin lymphoma. The diagnosis of MCL includes laboratory findings, lymph node biopsy, bone marrow evaluation, and imaging modalities such as computed tomography and magnetic resonance imaging. FDG PET imaging is also used in all kinds of lymphoma for staging, re-staging, and evaluating response to therapy. It has recently been reported that FDG PET/CT has a high sensitivity in detecting both nodal and extranodal disease in MCL (3,4).

MCL tends to involve extranodal sites, especially bone marrow, spleen, gastrointestinal tract, Waldeyer’s ring, skin, and ocular adnexa (5). Central nervous system involvement seems to occur in advanced disease, and is very rare (6).

Testicular involvement of MCL has been reported to be extremely rare. Epstein et al. (2) reported testis-isolated MCL in one case, while Licci et al. (7) described primary MCL of the testis in a patient. To the best of our knowledge, our case is the 8th reported MCL with testicular involvement, and is the first case which was demonstrated with PET/CT (1,8,9).

In the presented case, we observed a very high FDG avidity in metastatic lesions, for example left iliac lymph node conglomeration had a SUVmax of 57.5. Since some authors suggest that MCL could transform to a more aggressive form (4), the patient underwent core biopsy. In this case, PET/CT guided the physician to the most suitable and metabolically active site for tissue sampling, and the pathology report confirmed MCL with a pleomorphic variant.

PET/CT has an advantage of whole-body imaging and guidance for biopsy site in MCL. In this case, PET/CT demonstrated a very rare involvement of MCL in the testicles, and aided in clinical management.