Cytopathology Case 11

Cytologic Features:

• The cytology laboratory received 50 mL of clear fluid designated as vitreous fluid; one filter and one liquid-based slide were prepared, both stained with Papanicolaou stain.
• Both the filter and the cytospin showed an increased cellularity for vitreous fluid e and atypical lymphoid cells which nuclear membrane irregularities and prominent nucleoli (fig. 2).
• These findings were considered suspicious for involvement by lymphoproliferative disorder.
• Due to the cytologic findings and the pertinent history of peripheral T-cell lymphoma, a portion of the specimen was submitted for flow cytometric studies.
• Immunophenotypic analysis revealed a paucicellular specimen with creased viability and cellular debris that also included a small population of atypical T-cells that appeared to express CD3, weak CD2 and partial CD7, but not CD4, CD8 or CD30.
• These findings were suspicious for T-cell disorder, but not definite due to the decreased viability of the specimen.

Histologic Features:

• At the time of initial presentation two skin punch biopsies were received in the histology lad that were submitted.
• Microscopic examination of the punch skin biopsies revealed a dense, dermal infiltrate of large, atypical lymphocytes with irregular nuclear contours and nuclear hyperchromasia (fig. 3,fig. 4,fig. 5).
• There was also a focal epitheliotropism of similar appearing lymphocytes.
• PAS and gram stains were performed and were negative for organisms (not shown).
• Immunohistochemical stains were performed in one of the skin biopsies.
• The atypical cells were positive for CD3 (a pan-T-cell marker) and CD2, and positive for CD4, but negative for CD5, CD7, CD8, CD30, CD56, and CD20 (a pan-B-cell marker) (fig. 6).

DISCUSSION
Peripheral T-cell lymphomas (PTCLs) are a heterogeneous group of hematolymphoid malignancies derived from mature T-cells and natural killer (NK) cells, and represent approximately 12% of all non-Hodgkin lymphomas (NHL). Peripheral T-cell lymphoma, not otherwise specified (PTCL, NOS) is the most common group of PTCLs, accounting for 30% of cases worldwide. This is a default category for any mature T-cell neoplasm that does not be further classified in one of the specified categories according to the current World Health Organization (WHO) classification1. Patients typically present with advanced stage disease. The clinical course is aggressive and the response to conventional chemotherapy is indeed poor, with five-years event-free and overall survival around 20-30%. Extranodal involvement, including the skin, is very common, despite the fact that they were initially classified as “nodal” PTCLs.

The pathologic features of PTCL, NOS is extremely variable. The cytologic spectrum is broad, from highly polymorphous to monomorphous. Most cases consist of medium-sized and/or large cells with pleomorphic, hyperchromatic, vesicular nuclei with irregular nuclear contours and prominent nucleoli. These cytologic features were characteristically present on the cytospin preparation of the vitreous fluid specimen, supporting the clinical suspicion of secondary involvement of vitreous by T-cell lymphoma. Regarding the immunophenotypic characteristic, the neoplastic cells are CD4+ helper T-cells, and often show aberrant expression of one of the T-cell associated antigens (CD5 and CD7) that are commonly downregulated2,3. Approximately 30% of PTCL, NOS show partial CD30 expression. The phenotype plays a basic role in the distinction of PTCL, NOS from reactive conditions that can mimic malignant lymphoma, as well as for differential diagnosis among PTCLs. In fact, the lack of one or more T cell associated antigens is a hallmark of neoplastic cells.

Cases of intraocular lymphoma (B-cell or T-cell) either as primary or secondary following central nervouse system involvement have been described previously in the literature4,5. Diagnostic vitrectomy is the most common method used to confirm the clinical impression of intraocular lymphoma with vitreous aspiration needle tap. The clinical symptoms of blurry vision or floaters are an indication of vitreitis or uveitis. Cytologic examination of vitreous fluid has been shown to be a useful diagnostic tool to confirm the abnormally increased cellularity that in correlation with cytomorphologic features and the clinical scenario can support the diagnosis of intraocular lymphoma. However, the identification of malignant cells in vitrectomy samples can be confounded by the presence of reactive immune cells, necrotic cells, debris, and fibrin. Immunophenotypic analysis by flow cytometry of the vitreous fluid plays an important diagnostic role and is a strong diagnostic tool to further classify the lymphoid malignancy. Measurement of intraocular cytokine levels and molecular studies, including T-cell receptor for T-cell lymphomas or immunoglobulin gene rearrangement for B-cell lymphoma by PCR, have been suggested as additional diagnostic tests that may facilitate in the diagnosis.

A diagnosis of intraocular lymphoma should be considered for a patient with a history of uveitis and the presence of vitreous cells in sheets or clumps on funduscopic examination or retinal lesions. These patients with or without history of systemic involvement by lymphoma should undergo brain imaging and cerebrospinal fluid (CSF) examination. In patients with negative CSF, as in our case, a diagnostic vitrectomy and vitreous tap should be performed and the sample should be sent for cytologic examination and flow cytometry studies that will facilitate in diagnosis and further management of the patient.

References

1. Pileri S.A., Weisenburger D.D., Jaffe E.S. et al. Peripheral T-cell lymphoma, not otherwise specified. In: Jaffe ES, Harris NL, Stein H, Vardiman JW (eds.). World Health Organization classification of tumours Pathology and genetics of tumors of haematopoietic and lymphoid tissues. Lyon, France: IARC Press; 2008:306-308.
2. Macon W.R.. Peripheral T-cell lymphomas. Hem Oncol Clin N Am 2009; 23: 829-842.
3. O’Leary H., Savage K.J.. The spectrum of peripheral T-cell lymphomas. Current Opinion Hematol 2009; 16: 292-298.
4. Chan C., Wallace D.J.. Intraocular Lymphoma:Update on Diagnosis and Management. Cancer Control. 2004; 11(5): 285-295.
5. Chong D.Y., Johnson M.W., Shen D., Chan C., Callanan D.G. Vitreous Metastases of Primary Cutaneous B-Cell Lymphoma. Ocul Immunol Inflamm. 2009; 17(5): 342-344.