DOI: 10.1097/DAD.0b013e3181a772c6
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PMID: 19730085
Issn Print: 0193-1091
Publication Date: 2009/12/01
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Excerpt
Kimura disease (KD) is a chronic inflammatory condition of unknown etiology.1-5 This rare disorder, which occurs mainly in oriental Asians, generally involves the soft tissues of the head and neck area.1-5 Typically, peripheral blood eosinophilia and elevated serum levels of immunoglobulin (Ig) E are found in these patients.1-5 A nephrotic syndrome due to glomerulonephritis may also occur in a certain number of cases.1-5 To date, the pathogenesis of such disorder is still enigmatic; an autoimmune or allergic origin has been suggested by some authors, owing to the eosinophilic hyperplasia, raised IgE amounts, and T helper 2 (Th2) cytokine profile of T lymphocytes, seen in this condition.2-5 We report the case of a 47-year-old North African male who developed a KD involving the subcutis of the retroauricular area. The presence of numerous plasmacytoid dendritic cells (PDCs) in the lesion, a feature rarely described in KD, may unravel in part the pathophysiology of the disease.
The patient had no medical history apart from a right chronic maxillary sinusitis treated by surgery several years ago. He spontaneously developed a 25 × 15 × 10-mm subcutaneous swelling in the right postauricular area. Physical examination and imaging studies did not disclose any other anomaly. The mass was excised for diagnostic purposes.
Microscopic examination demonstrated a well-circumscribed lymph node-like lymphoid nodule located in the subcutis (Fig. 1A). Lymphoid follicles were present and featured variably developed germinal centers. These structures occasionally contained multinucleate follicular dendritic cells (DCs) or small deposits of proteinaceous material. There was a prominent eosinophilic infiltrate involving the lymphoid follicles and the interfollicular areas. Fibrotic changes were seen within the interfollicular zones and around blood vessels. In some places, there were occasional epithelioid histiocytes or epithelioid granulomas with central eosinophilic abscesses. Interestingly, numerous clusters of PDCs were found in the vicinity of high endothelial venules or at the periphery of lymphoid follicles (Fig. 1B). These clusters were usually loose in comparison with the dense clusters normally observed in reactive lymph nodes and contained lymphocytes and eosinophils (Fig. 1B). The overlying skin contained a moderate lymphoid infiltrate made of small lymphocytes, histiocytes, eosinophils, and PDCs, in varying proportions. This lymphoid infiltrate was mostly located around dermal vessels and cutaneous adnexae. Notably, the epidermis did not demonstrate any significant changes. On immunohistochemical analysis, CD20-positive B cells formed the lymphoid follicles, whereas most of interfollicular lymphocytes showed immunoreactivity with antibodies directed against CD3, CD4, or CD8. As a rule, CD4-positive cells outnumbered CD8-positive lymphocytes. Epithelioid histiocytes or epithelioid granulomas consistently expressed CD68 and at variable extent also displayed CD163 immunoreactivity. DCs expressing S100 protein or CD1a were found throughout the lymphoid tissue, and CD1a-positive DCs were focally relatively numerous. PDCs expressed CD4, CD68, granzyme B, and CD123. These cells were also positive for BCL11a, CD2-associated protein (CD2AP), and blood dendritic cell antigen 2 but were negative for CD56 (Figs. 1C, D). Polymerase chain reaction analysis of DNA extracted from paraffin-embedded sections did not demonstrate any clonal rearrangement of the genes coding for the Ig heavy (IgH) chain and for the γ subunit of the T-cell receptor.
Based on these data, a diagnosis of KD featuring a significant number of PDCs was rendered. Additional investigations revealed the presence of a moderate increase in eosinophil counts in the peripheral blood (white blood cells: 9.5 × 109/L: 15% eosinophils) and raised IgE serum levels (198 IU/mL), which confirmed the diagnosis. Serum titers of IgM, IgG, and IgA, and serum levels of several proteins of the complement system (C1q, C3, and C4), were within normal limits. Renal function tests were normal. Serologic studies for rheumatoid factor or anti-DNA antibodies were negative.
