Lymphoma & related disorders

Contributed by Carlos A. Murga-Zamalloa, M.D.

The image depicts EBER in situ hybridization in a lymph node. Which of the following is true regarding EBV+ nodal T and NK cell lymphoma?

1. EBV is positive in background nonneoplastic B cells
2. Expression of the cytotoxic marker TIA1 and granzyme B is usually absent
3. Most cases are CD3 / CD4 positive, while CD3 / CD8 positive cases are infrequent
4. TCR alpha / beta is more common than TCR gamma / delta expression
5. Usually features a good prognosis with response to anthracycline based chemotherapy

D. TCR alpha / beta is more common than TCR gamma / delta expression. More cases feature TCR alpha / beta expression (~50%) rather than TCR gamma / delta (5%). Answer A is incorrect because in contrast to angioimmunoblastic T cell lymphoma, EBV infection drives the oncogenic process and is positive in the neoplastic T cells and not in the background B cell lymphocytes. Answer B is incorrect because this subtype of T cell lymphoma is characterized by the expansion of cytotoxic T cell lymphocytes with frequent expression of TIA1 and granzyme B. Answer C is incorrect because most cases reported feature neoplastic T cells that are CD3 / CD8 positive; < 5% reported feature CD3 / CD4 positive neoplastic T cells. Answer E is incorrect because patients with a diagnosis of EBV+ nodal T and NK cell lymphoma have poor response to standard chemotherapeutic agents and a median survival of 3 - 8 months.

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Reference: EBV+ nodal T and NK cell lymphoma

The image depicts EBER in situ hybridization in a lymph node. Which of the following is true regarding EBV+ nodal T / NK cell lymphoma?

1. By definition, > 80% EBER positivity of the tumor cells are required for the diagnosis of EBV+ nodal T / NK cell lymphoma
2. Expression of CD30 is detected in most cases
3. Mutations in the RHOA gene are frequently detected in this lymphoma
4. There is an overlap in immunophenotypic features with systemic EBV positive T cell lymphoma (SETBL) of childhood; however, EBV+ nodal T / NK lymphoma is predominantly detected in adult populations with primarily nodal disease
5. This group of T cell lymphomas is clinically characterized by primary orofacial involvement with secondary nodal disease

D. There is an overlap in immunophenotypic features with systemic EBV positive T cell lymphoma (SETBL) of childhood; however, EBV+ nodal T / NK lymphoma is predominantly detected in adult populations with primarily nodal disease. SETBL and EBV+ nodal T / NK lymphoma constitute neoplastic proliferations of cytotoxic T cell lymphocytes; however, SETBL is diagnosed in pediatric populations and EBV+ nodal T / NK lymphoma is predominantly detected in adult populations. Answer A is incorrect because there are no established criteria regarding the percentage of neoplastic T cells for diagnosis; however, many reports included cases with 30% of neoplastic tumor cells positive for EBV by EBER in situ hybridization. Answer B is incorrect because expression of CD30 can be detected in ~20% of the cases and when positive, only a limited number of neoplastic T cells are positive. Answer C is incorrect because mutations in RHOA are predominantly detected in peripheral T cell lymphomas of the T follicular helper type (TFH type), not in EBV+ nodal T / NK lymphomas. Answer E is incorrect because in contrast to extranodal T / NK nasal type lymphoma, EBV+ nodal T / NK lymphoma is primarily nodal without involvement of extranodal sites in the nasal cavity, nasopharynx, oropharynx, Waldeyer ring and epiglottis.

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Reference: EBV+ nodal T and NK cell lymphoma