Lymphomatoid papulosis with CD1a+ dendritic cell hyperplasia, mimicking Langerhans cell histiocytosis.
Although CD1a+ dendritic cells (DC) in cutaneous T-cell lymphomas (CTCL) have been well documented, the presence of large numbers of DC within lymphoid infiltrates can pose a diagnostic difficulty. We present a case of a 70-year-old man with a 3-year history of recurrent red papules and plaques on the extremities and trunk that was referred to our institution, with the diagnosis of Langerhans cell histiocytosis. Skin biopsies showed a wedge-shaped cellular infiltrate in the superficial and deep dermis consisting of two cell populations. Most prominent were clusters of epithelioid cells with grooved nuclei and abundant eosinophilic cytoplasm, which stained with antibodies to CD1a and S-100. A second, less prominent population of atypical lymphocytes, some with enlarged, hyperchromatic and convoluted nuclei, were intermixed. The latter were positive for CD30, CD3 and CD5 and negative for CD20, CD34, CD68, ALK-1 and TdT. T-cell receptor gene rearrangement studies confirmed a clonal T-cell population, which with the clinical history was consistent with the diagnosis of lymphomatoid papulosis. While previous studies have shown an increased density of dermal DC in CTCL, we believe that this represents the first report of an unusually florid DC proliferation mimicking Langerhans cell histiocytosis and masking a lymphoproliferative disorder.
Jokinen
Chris H
CH
Department of Pathology, University of Washington, Seattle, WA 98195, USA.
Wolgamot
Gregory M
GM
Wood
Brent L
BL
Olerud
John
J
Argenyi
Zsolt B
ZB
D000368:Aged; D018949:Antigens, CD1 / Q000378:metabolism*; D014408:Biomarkers, Tumor / Q000378:metabolism; D003713:Dendritic Cells / Q000378:metabolism / Q000473:pathology*; D003879:Dermatologic Agents / Q000627:therapeutic use; D003937:Diagnosis, Differential; D006646:Histiocytosis, Langerhans-Cell / Q000175:diagnosis* / Q000378:metabolism; D006801:Humans; D006965:Hyperplasia; D017731:Lymphomatoid Papulosis / Q000188:drug therapy / Q000378:metabolism / Q000473:pathology*; D008297:Male; D008727:Methotrexate / Q000627:therapeutic use; D016896:Treatment Outcome
D018949:Antigens, CD1; D014408:Biomarkers, Tumor; C419393:CD1a antigen; D003879:Dermatologic Agents; D008727:Methotrexate