Lymph Node Lesion of Acute Infectious Mononucleosis in the Elderly : A Case Report

Abstract

We present here lymph node lesion of infectious mononucleosis (IM) in an elderly patient. An 80-year-old Japanese woman presented with a 1 month history of left supraclavicular lymphadenopathy accompanied by high-grade fever, general fatigue and swelling in the bilateral submandibular gland region. Physical examination on admission demonstrated systemic lymphadenopathy up to 40 mm in diameter. The hemoglobin was 12.0 g/dL, white blood cell count 10.5 × 10/L (atypical lymphocytes 25%) (Fig. 1a) and platelet count 205 × 10/L. Serum protein electrophoresis demonstrated a polyclonal hyper-gglobulinemia. Measurement of serum immunoglobulin (Ig) levels demonstrated the following : IgG 4,856 mg/dL, IgA 707 mg/dL and IgM 314 mg/dL. Subsequent serologic tests for Epstein-Barr virus (EBV) showed a previous infection pattern : a viral capsid antigen (VCA) IgG titer of 4.5 (< 0.5 mg/dL), a VCA IgM titer of 0.0 (< 0.5 mg/dL), an early antigen (EA) IgG titer of 0.2 (< 0.5 mg/dL), and an EBV nuclear antigen (EBNA) titer of 1.5 (< 0.5 mg/dL). However, abnormal high titer of EBVDNA (7.6 × 10 ; normal range < 2.0 × 10) was detected in peripheral blood. Cervical lymph node biopsy was performed. Information from flow cytometry of the biopsied specimens showed a polyclonal B cell population. There was no absence of panT-cell markers. The patient treated with prednisolone, and she is currently alive without disease 14 months after disease onset. Tissue specimens were fixed in formalin solution, routinely processed and embedded in paraffin. For light microscopic examination, the sections were stained with hematoxylin-eosin (HE). Immunohistochemical studies were performed using the antigen retrieval method on the Histofine Histostainer (Nichirei Bioscience Inc, Tokyo, Japan) according to the manufacturer’s instructions. The panel of antibodies included, human immunoglobulin light chains (k and l), SP7 (CD3), 4C7 (CD5), L26 (CD20), MCS-1 (CD15), and CD30 (1G12) (Nichirei). Sections with known reactivity for antibodies assayed served as positive controls and sections treated with normal rabbit and mouse serum served as negative controls. In situ hybridization (ISH) with EBV-encoded small RNA (EBER) oligonucleotides was also performed to test for the presence of EBV small RNA in formalin-fixed paraffinembedded sections using the hybridization kit (Dako A/S, Glostrup, Denmark). DNA was extracted from paraffin-embedded sections. The variable region (CDR2 and FW3) and VDJ region (CDR3) of immunoglobulin heavy chain (IgH) gene were amplified by semi-nested PCR, using primers of FR2B, LJH and VLJH, according to a previously described method. Primers were as follows: 5’-CCGG (A/G) AA (A/G) (A/G) GTCTGGAGTGG-3’, as upstream consensus V region primer (FR2B) ; 5’-TGAGGAGACGGTGACC-3’, as a consensus J region primer (LJH) ; 5’-GTGACCAGGGT [A/C/G/T] CCTTGGCCCCAG-3’, as a consensus J region primer (VLJH). PCR products were estimated to be about 200-300 bps in length. Histologically, on low power field, the biopsied specimens demonstrated numerous lymphoid follicles with normal or atrophic germinal centers and interfollicular widening (Fig. 1b). Marked proliferation of arborizing vessels was noted in the interfollicular area (Fig. 1b). The lymphoid sinuses occasionally appeared to be compressed by the paracortical expansion. The paracortical area and medullary cords were heavily infiltrated with small and medium-sized lymphocytes, mature plasma cells, plasmacytoid cells, immature plasma cells, im-