1. 인하대병원 전공의 최창환

2. Clinical history  33 세, 남자  좌측 경부 콩알크기 종괴 (1 개월전 )  U/S: 좌측 level I, II, III, IV 에 커진 림프절 ( 최 대 3.1cm)  결핵성 림프절염 혹은 비특이적 림프절염 의 심하 초음파 유도하 세포검사

10. Microscopic findings  Loose cohesive and discohesive cells  Spindle and epithelioid cells Bi- or multipolar cytoplasmic process Indistinct cell borders Ovoid or elongated nuclei ○ Mild to prominent nuclear atypia ○ Pale vesicular chromatin ○ Delicate nuclear membrane Small but distinct nucleoli  Admixture of atypical cells and bland-looking mature lymphocytes with inflammatory background

11. Differential diagnosis  Spindle cell lesion involving multiple lymph nodes of neck No systemic symptom No granuloma No necrosis Moderate cellular atypia Non-neoplastic lesion Infection bacteria mycobacterium virus fungus Sarcoidosis Inflammatory pseudotumor Neoplastic lesion Dendritic cell neoplasm Lymphoma Langerhans cell histiocytosis Thymoma Carcinoma Melenoma

12. Differential diagnosis  Dendritic cell neoplasm  Lymphoma  Langerhans cell histiocytosis / Sarcoma  Thymoma  Metastatic carcinoma  Metastatic melanoma  Inflammatory pseudotumor

13. Differential diagnosis  Dendritic cell neoplasm  Lymphoma  Langerhans cell histiocytosis / Sarcoma  Thymoma  Metastatic carcinoma  Metastatic melanoma  Inflammatory pseudotumor No cytoplasmic process Spindle cells without atypia Many inflammatory cell (plasma cells) Vascular proliferation

14. Differential diagnosis  Dendritic cell neoplasm  Lymphoma  Langerhans cell histiocytosis / Sarcoma  Thymoma  Metastatic carcinoma  Metastatic melanoma No cytoplasmic process Obviously malignant cell Macronucleoli Fine brown pigments in cytoplasm

15. Differential diagnosis  Dendritic cell neoplasm  Lymphoma  Langerhans cell histiocytosis / Sarcoma  Thymoma  Metastatic carcinoma Spindle cell carcinoma or lymphoepithelioma-like carcinoma No cytoplasmic process Tightly clustered tumor cells and more pleomorphic cells Unevenly crowded overlapping nuclei Tumor necrosis

16. Differential diagnosis  Dendritic cell neoplasm  Lymphoma  Langerhans cell histiocytosis / Sarcoma  Thymoma No cytoplasmic process Cohesive fascicles and whorls of spindle cells Inconspicuous nucleoli Fibrovascular core with arborizing capillary

17. Differential diagnosis  Dendritic cell neoplasm  Lymphoma  Langerhans cell histiocytosis / Sarcoma Grooved, folded, indented or lobulated nuclei Admixed with variable numbers of eosinophils, hisitocytes, neutrophils and small lymphocytes Very large cell with round or folded nuclei

18. Differential diagnosis  Dendritic cell neoplasm  Lymphoma Spindle cell variant of DLBCL, ALCL, nodular sclerosis Hodgkin lymphoma No cytoplasmic process More irregular nuclear membrane More granulocytes in background

19. Differential diagnosis  Dendritic cell neoplasm Follicular dendritic cell sarcoma Interdigitating dendritic cell sarcoma Fibroblastic reticular cell tumor Indeterminate dendritic cell tumor

20. Interdigitating dendritic cell sarcoma Follicular dendritic cell sarcoma KCP 797 AgePredominantly adults 33year-old GenderSlightly male predominanceNo gender predilectionMale Lymph nodeSolitary50-70% lymphadenopathyMultiple neck node enlargement Growth pattern Paracortical Fascicles, storiform arrays, whorls Diffuse sheets or vague nodules Fascicles, storiform arrays, whorls Cellular feature Spindled to ovoid Indistinct cell border Abundant cytoplasm Spindled to ovoid Indistinct cell border Cytoplasmic process Spindled to ovoid Indistinct cell border Cytoplasmic process MitosisLow(<5/10HPF)Variable(0-10/10HPF)Inconspicuous(0-1/10HPF)

21. Diagnosis  KCP 797 Lymph node, left level II, neck, US-guided FNA cytology: Dendritic cell neoplasm, most likely f ollicular dendritic cell sarcoma