Fluoro-deoxy glucose positron emission tomography-computed tomography in a case of natural killer/T-cell lymphoma with bilateral adrenal involvement

INTRODUCTION

Natural killer/T-cell (NK/T-cell) lymphoma is a rare fast-growing lymphoma arising from the lining of the nose or upper airway. They usually present with epistaxis and swelling. We report an interesting case who also had bilateral adrenal involvement.

CASE REPORT

A 26-year-old young female presented with nasal obstruction, bloody discharge and swelling of the nasal skin and right lower eyelid. Biopsy from the soft tissue seen in the nasal cavity revealed NK/T-cell lymphoma (nasal type). Patient was referred to a whole body 18 fluoride (18F)-fluoro-deoxy glucose (FDG) positron emission tomography-computed tomography (PET-CT). 18F-FDG PET-CT performed showed intense FDG uptake in heterogeneously enhancing soft tissue in the right nasal cavity with extension into the skin of the cheek and right lower eyelid [Figure 1: a - maximum-intensity projection, b - axial CT, c - fused PET-CT]. Intense FDG uptake was also noted in enhancing soft tissue bilateral adrenal masses [d - axial CT; e - fused PET-CT] indicating disease involvement. A diagnosis of bilateral adrenal involvement by NK/T-cell lymphoma was made. Patient was referred back to medical Oncology Department for chemotherapy.

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Figure 1 18 Fluoride-fluoro-deoxy glucose positron emission tomography-computed tomography (18F-FDG PET-CT) performed showed intense FDG uptake in heterogeneously enhancing soft tissue in the right nasal cavity with extension into the skin of the cheek and right lower eye lid (a - maximum-intensity projection, b - axial CT, c - fused PET-CT). Intense FDG uptake was also noted in enhancing soft tissue bilateral adrenal masses (d - axial CT; e - fused PET-CT) indicating disease involvement

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DISCUSSION

Natural killer cells mediate lysis of tumor cells, bacteria or virus infected cells. They also aid in the production of immunomodulatory cytokines. Morphologically, mature NK cells are large granular lymphoid cells, they are negative for surface CD3 but characteristically express cytoplasmic CD3 epsilon (ε), CD56, and cytotoxic molecules. There are two main categories of NK cell-derived neoplasms, namely, aggressive NK cell leukemia and extranodal NK/T-cell lymphoma, nasal type. Epstein–Barr virus infection in the lymphoma cells is a consistent finding.[1] NK/T-cell lymphoma of the nasal type accounts for 7–10% of all non-Hodgkin lymphomas in Asia and Latin America, but only 1% of that amongst Caucasians.[2] The leukemic counterpart of NK/T-cell lymphoma, aggressive NK-cell leukemia is an uncommon disease. Clinically, it is useful to classify NK/T-cell malignancies into two categories, namely, nasal NK-cell lymphomas, and nonnasal or extranasal NK/T-cell lymphomas, depending on the site of the lesions. Nasal NK/T-cell lymphomas occur in the nose and the upper aerodigestive tract. Nasal obstruction, facial swelling, and epistaxis are the common presentations. Bone marrow involvement occurs in <10% of patients, and distant metastasis is unusual.[3]

Extranasal or nonnasal NK/T-cell lymphomas occur outside the typical nasal region, and the common primary sites involved include the skin, gastrointestinal tract, salivary glands, spleen, and testis. Unusual sites of involvement such as the muscle, the adrenal gland, and the female genital tract (ovaries and uterus) have been reported.[4] Occult nasal involvement should be ruled out with panendoscopy and multiple random biopsies in patients presenting with extranasal NK/T-cell lymphoma. Disseminated nodal NHL can involve the adrenals in up to 25% of the cases.[56] However, primary adrenal lymphoma is extremely rare with majority of the cases being B cell type.

Natural killer-cell lymphomas are FDG-avid and PET-CT offers more accurate definition of the extent of involvement by distinguishing lymphoma involvement from inflammatory masses. 18-FDG PET-CT is increasingly used both at diagnosis and for monitoring of response to therapy.[789] PET changes the staging in up to 21% of the patients and alters the planned management strategy in 44% of the patients.[7] PET parameters such as total lesion glycolysis, in addition to the international prognostic index, is useful in predicting prognosis of these patients.[9]

For the stage, I/II nasal NK/T-cell lymphomas, radiotherapy is an important modality of treatment. Recent evidence indicates radiation therapy alone is insufficient, and chemotherapy is also needed in these patients. Nonnasal NK cell lymphomas tend to have advanced or disseminated disease at presentation, and the role of radiotherapy is often limited. For the stage III/IV nasal NK/T-cell lymphomas, extranasal NK/T-cell lymphomas and aggressive NK-cell lymphoma/leukemia, chemotherapy is the primary treatment. L-asparaginase-containing regimens have shown promise as the tumor cells lack L-asparagine synthetase and are susceptible to L-asparaginase, which depletes L-asparagines in NK lymphoma cells.[10]