RESUMO
<p><b>OBJECTIVE</b>To report a case of interdigitating dendritic cell sarcoma (IDCS).</p><p><b>PATIENT MATERIAL</b>The patient was a 41-year-old man with a lymph node bulging in the left neck. Laboratory examination of peripheral blood and bone marrow was abnormal. The diagnosis of IDCS was made by immunohistochemistry and electron microscopy. Treatment of this patient with ABVD regimen (adriamycin, bleomycin, vinblastine, dacarbazine) resulted in obvious improvement, but did not control the tumor infiltration.</p><p><b>CONCLUSION</b>IDCS has no distinctive clinical or pathohistological characteristics. Immunohistochemistry and electron microscopy are crucial in distinguishing it from other histiocytic/dendritic cell neoplasms. IDCS displays an aggressive behaviour, and the responses to chemotherapy are variable.</p>