Natural killer cell lymphoma in cytology: breaking all the rules--a case report

Spectrum of cytomorphological features of extranodal NK/T-cell lymphoma, nasal type

OBJECTIVE

Extranodal natural killer/T-cell lymphoma, nasal type (ENKTL) is an aggressive extranodal lymphoma of NK-cell or T-cell lineage. Its clinical features overlap with those of several sinonasal mass lesions. While the histopathological features are well described, diagnosis is often difficult, owing to presence of extensive coagulative necrosis, so that repeated biopsies may sometimes be necessary for correct diagnosis. Literature on cytological findings of ENKTL is limited.

METHODS

Cytomorphological features of cases of histologically confirmed ENKTL having corresponding cytology samples were reviewed retrospectively, to identify distinctive features that could possibly suggest this entity.

RESULTS

Aspirates from five patients were studied: four from cervical nodes, one from cheek swelling and one from pleural fluid. Two aspirates were reported as positive for malignancy, two as atypical lymphoid proliferation and one was non-diagnostic. Pleural fluid was reported as malignant, favouring a diagnosis of carcinoma. On cytology, aspirates showed medium to large cells with folded, indented nuclei and abundant pale cytoplasm, some with tongue-like cytoplasmic protrusions. A distinctive feature was presence of large loose clusters of tumour cells with arborising capillaries running through them. Interestingly, necrosis was consistently absent. Subsequent biopsies from palate (three cases) and nasal masses (two cases) confirmed the diagnosis of ENKTL.

CONCLUSIONS

Suspicion of ENKTL on cytology is crucial for timely diagnosis to avoid diagnostic delay, especially when only highly necrotic biopsy samples are available. Awareness of distinctive cytomorphological features is required to make fine needle aspiration an effective diagnostic tool for initial diagnosis and for evaluation of possible recurrences.

Comparison of Diagnostic Cytomorphology of Natural Killer/T-Cell Lymphoma (Nasal Type) in Conventional Smears, Liquid-Based Preparations, and Histopathology

Natural killer (NK)/T-cell lymphoma is formally referred to as extranodal NK/T-cell lymphoma, nasal type (ENKTCL), in the 2008 and 2016 World Health Organization (WHO) classifications. NK/T-cell lymphoma, nasal type, is a rare but clinically important lymphoid neoplasm. It is the predominant type of extranodal lymphoma associated with the Epstein–Barr virus (EBV). NK/T-cell lymphoma is marked by a wide cytomorphological spectrum. The cytological findings may be so subtle that NK/T-cell lymphoma could possibly be easily overlooked. Here, we report a case of NK/T-cell lymphoma involving the sinonasal region with lymph node involvement. Fine needle aspiration of the neck lymph node and punch biopsy of the nasal mucosa were performed. The diagnosis of NK/T-cell lymphoma was confirmed based on pathological and immunohistochemical analyses, as well as in situ hybridization for EBV-encoded mRNA (EBER). The present case report underlines the importance of prompt clinicopathological assessment in suspected cases. The comparison of cytomorphologic features of NK/T-cell lymphoma in various specimens is presented.

Extranodal NK/T-cell lymphoma, nasal type of the uterine cervix: A case report

We report a rare case of extranodal NK/T-cell lymphoma, nasal type of the uterine cervix that showed cytologic features mimicking cervical cancer. A 65-year-old woman presented with vaginal bleeding. Gynecological examination revealed a bulky tumor of the cervix. A conventional Papanicolaou-stained cervical smear showed hypercellularity consisting of numerous variably sized cohesive clusters that mimicked epithelial tumors, with a necrotic and inflammatory background. A small number of individually scattered cells were also identified. These scattered cells showed pleomorphic, often cleaved, or horseshoe-shaped nuclei and pale cytoplasm. Biopsy specimens revealed a diffuse growth of atypical cells with an angiocentric pattern. Extensive necrosis and infiltration of inflammatory cells were present. There were numerous mitotic figures. The tumor cells were positive for CD45RO, CD3ε, CD56, granzyme B, TIA-1, CD7, and Epstein-Barr virus (EBV)-encoded small RNA (EBER) by in situ hybridization, and negative for cytokeratin, chromogranin A, synaptophysin, CD4, CD5, CD8, CD20, and CD30. Based on these findings, this tumor was diagnosed as extranodal NK/T-cell lymphoma, nasal type of the uterine cervix.

Histopathologic and Molecular Aspects of CD56+ Natural Killer/ T-Cell Lymphoma of the Testis

Primary nasal-type natural killer/T-cell lymphoma of the testis is a rare malignancy. Although dissemination to the testis from other sites occurs somewhat more frequently than a primary presentation, even secondary testicular involvement is uncommon. In this article, the authors report on the comprehensive histopathologic, immunohistochemical, and molecular analysis of a case of primary testicular nasal-type natural killer/T-cell lymphoma, and review the features of 16 previously reported patients. The investigation carried out in this study indicates that the testicular nasal-type natural killer/T-cell lymphomas occur at a younger age than their B-cell counterparts, express cytoplasmic CD3 and surface CD56, and consistently show an infection by Epstein-Barr virus. These tumors have variable expression of T-cell antigens other than cytoplasmic CD3 and may show monoclonal rearrangement of T-cell receptor genes. Testicular natural killer/T-cell lymphomas of nasal type invariably follow an aggressive clinical course.

Fine-needle aspiration cytology of blastic natural killer-cell lymphoma (CD4+ CD56+ hematodermic neoplasm)

We describe fine-needle aspiration (FNA) cytology findings of a case of blastic natural killer (NK)-cell lymphoma. The patient was a 68-year-old man who was diagnosed with cutaneous blastic NK-cell lymphoma involving his forehead. He developed a 1.5 cm, right pre-auricular lymph node five months later. FNA cytology revealed a monomorphic population of medium-sized lymphoid cells with a dispersed single cell arrangement. The tumor cells contained eccentrically located nuclei with a plasmacytoloid appearance and moderate amount of grayish cytoplasm without azurophilic granules. The nuclei were round to oval with fine chromatin, small indistinct nucleoli, and frequent nuclear indentation. Many cells also showed elongated cytoplasm with a unique hand-mirror or ping-pong paddle-like appearance. The flow cytometry study obtained during the FNA revealed co-expression of CD4 and CD56 in the tumor cells that confirm the recurrence of a blastic NK-cell lymphoma to the pre-auricular lymph node.

Fine needle aspiration cytology of CD56-positive natural killer/T-cell lymphoma of soft tissue

BACKGROUND

Extranodal natural killer (NK)/T-cell lymphoma, nasal type, is a rare form of lymphoma with a predilection for Southeast Asians, including Koreans, and Central and South Americans. It has a high association with Epstein-Barr virus (EBV) and expression of CD56 antigen. In the current study, the authors reviewed the fine needle aspiration (FNA) cytology of NK/T-cell lymphoma involving soft tissue to identify characteristic cytologic features.

METHODS

Ten FNAs of soft tissue involvement by histologically documented NK/T-cell lymphoma from eight patients (three nasal primary and five extranasal primary tumors) were included in the retrospective study of a six-year period (1996-2002). Diff-Quik- and Papanicolaou-stained smears were reviewed, as was the biopsy material, including immunohistochemical stains and in situ hybridization studies for EBV. Clinical information was obtained from the patients' medical records.

RESULTS

Specimen sources were skin and subcutaneous tissue of the neck (3), arm (3), breast (2), and abdominal wall (1) and soft tissue of the buccal area (1). The smears were moderately to highly cellular in the extensively necrotic background, with an abundance of apoptotic debris. Single, scattered tumor cells had pleomorphic nuclei, coarse chromatin, indistinct or several small nucleoli, and eccentric bluish cytoplasm. Neutrophils were typically rare in most cases except in one case complicated by abscess.

CONCLUSIONS

Fine needle aspiration can be a useful adjunct in the diagnosis of the nasal and extranasal NK/T-cell lymphoma. The presence of malignant lymphoid cells in a necrotic background with an abundance of apoptotic bodies is a highly characteristic and consistent finding in FNA of NK/T-cell lymphoma involving soft tissue.

Fine-needle aspiration cytology of extranodal natural killer/T-cell lymphoma

Extranodal NK/T-cell lymphoma, nasal type, is a predominantly extranodal lymphoma characterized histologically by prominent necrosis, angiocentric growth, and vascular destruction. Only one report describing its fine-needle aspiration (FNA) cytologic features is available and shows highly unusual findings for a lymphoma. The present case concerns a 58-yr-old patient that presented with a soft tissue mass of the thigh in addition to an ulcerative lesion of the palate and nodular hepatic and splenic lesions. FNA cytology of the thigh tumor was interpreted as a malignant mesenchymal lesion (sarcoma). The subsequent pathologic study revealed an NK/T-cell lymphoma. Our findings are very similar to those previously reported. They were highly unusual for a lymphoma and consisted of polymorphic, round to spindle neoplastic cells distributed in irregular aggregates, and single cells. No significant number of lymphoglandular bodies were present.

TIA-1+ cytotoxic large T-cell lymphoma of the mediastinum: case report

A 52-year-old previously healthy Caucasian woman presented with superior vena cava syndrome, secondary to compression of a bulky anterior mediastinal mass involving the right lung. Fine-needle aspiration biopsy of the mediastinum yielded large epithelioid cells intermingled with small mature lymphocytes. The epithelioid cells are LCA positive, expressing cytoplasmic CD3 diffusely and TIA-1 focally, but negative for EMA, CD4, CD8, CD15, CD20, CD30, and CD56. The TIA-1+ cytoplasmic granules correlated to the azurophilic granules in Diff-Quik-stained cells, pink granules in Ultrafast Papanicolaou-stained cells, and dense core granules in electron microscopy. In situ hybridization for Epstein-Barr viral RNA was negative. The background small lymphocytes were composed of a majority of CD4+ T-lymphocytes and minority of CD8+ T-lymphocytes. The patient responded well to six cycles of CHOP chemotherapy, followed by radiation with a total dose of 4140 cGy delivered to the mediastinum in 23 fractions. On the chest X-ray taken 6 mo later, there was minimal apical fibrosis with no evidence of an acute intrathoracic pathology. To the best of our knowledge, this case may be the first report of cytotoxic large T-cell lymphoma of the mediastinum.