[519] CD1a+ Cutaneous Dendritic Cells, Langerhans Cells and Interleukin 3 Receptor (CD123) in Reactive and Neoplastic Cutaneous Lymphoid Proliferations

S Kondratiev, O Barak, JJ O'Brien, M Pilichowska. Tufts Medical Center, Boston, MA

Background: Distinguishing reactive cutaneous lymphoid infiltrates from neoplastic proliferations can be difficult. Cutaneous CD1a expressing dendritic cells (CDCs) and Langerhans cells (LHCs) play crucial role in skin immune responses and T-cell proliferation. Interleukin-3 (IL-3) secreted by T cells promotes proliferation and differentiation of dendritic cells. We examined distribution of CD1a+ CDCs, LHCs and expression of IL-3 receptor (IL-3R; CD123) in a variety of reactive, neoplastic and pseudoneoplastic cutaneous lesions.
Design: 55 skin biopsies were retrieved form pathology archives. The diagnostic categories included: arthropod bite (13), Langerhans cell histiocytosis (4), juvenile xanthogranuloma (JXG;15), reticulohistiocytoma (RH;3), B-cell lymphoma (5), CD30+ T-cell lymphoma (2), mycosis fungoides (MF;2), lymphomatoid papulosis (LYP;1), atypical T-cell infiltrate (1), peripheral T-cell lymphoma (1) and angiolymphoid hyperplasia with eosinophilia (ALHE; 8). Immunoperoxidase staining for CD1a and IL-3R (CD123) was performed with commercially available antibodies. Quantity, distribution, morphology and staining intensity of CD1a+ CDCs, LHCs and cells expressing CD123 were recorded.
Results: All arthropod bites showed transdermal perivascular CD1a+ CDCs with mature morphology and prominent CD123+ cells in association with perivascular lymphoid infiltrates. In T-cell lymphomas (4/5), LYP, and atypical T-cell infiltrate CD1a+ CDCs were absent or infrequent. One case of MF showed prominent CD1a+ CDCs in the dermal papillae and associated prominent LHCs. CD123+ cells were prominent in the dermis in LYP, atypical T-cell infiltrate, and one case of CD30+ T-cell lymphoma. A subset of neoplastic cells in one CD30+ T-cell lymphoma case was positive for CD123. Most JXG (14/15) and RH (2/3) did not contain significant CD1a+ CDCs or CD123+ cells. ALHE demonstrated variable CD1a+ CDCs and CD123+ cells. In Langerhans cell histiocytosis neoplastic cells showed immature phenotype with membranous and cytoplasmic CD1a staining. Associated CD123+ cells were single and scattered. In B-cell lymphomas CD1a+ CDCs and CD123+ cells were rare.
Conclusions: IL-3R (CD123) plays a possible pathogenetic role in a subset of cutaneous T-cell neoplasms. It can be a useful tool in evaluation of atypical cutaneous lymphoid infiltrates, especially when combined with CD1a. Prominent perivascular intradermal CD1a+ CDCs, particularly in association with CD123 positive cells, favor reactive process.
Category: Dermatopathology

Wednesday, March 24, 2010 1:00 PM

Poster Session VI # 99, Wednesday Afternoon


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