Lymph nodes & spleen, nonlymphoma

• Wide age range; median age is 50 years (Crit Rev Oncol Hematol 2013;88:253)
• M = F

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• Low grade sarcoma that has significant recurrence rate (~40 - 50%) and can metastasize (Cancer 1997;79:294)
• Poor prognostic factors include size of tumor (> 6 cm), nuclear pleomorphism, increased mitoses (> 5/10 HPF), necrosis and intra-abdominal location (Arch Pathol Lab Med 2017;141:596)
• Inflammatory pseudotumor-like follicular dendritic cell sarcoma of the liver or spleen shows indolent behavior without recurrence (Am J Surg Pathol 2001;25:721)
• Association with paraneoplastic autoimmune multiorgan syndrome follows an aggressive course related to respiratory morbidity and mortality (Am J Surg Pathol 2018;42:1647)

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• Usually round to ovoid, well circumscribed fleshy solid mass (Arch Pathol Lab Med 2016;140:186)
• Size ranges from 1 - 15 cm, largely dependent on the site of the tumor
• May show areas of hemorrhage and necrosis

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• Oval to spindled cells with dispersed chromatin, small nucleoli, eosinophilic and fibrillar cytoplasm with syncytial borders arranged in fascicles, whorls or storiform patterns
• Often binucleate or occasional multinucleate forms, nuclear pseudoinclusions
• Perivascular lymphocyte cuffs and admixed population of lymphocytes, eosinophils, plasma cells or neutrophils may be present (Am J Surg Pathol 2004;28:988)

Contributed by Aishwarya Ravindran, M.B.B.S. and Karen L. Rech, M.D.

Contributed by Genevieve M. Crane, M.D., Ph.D.

AFIP images

• Lymph node, left neck, excisional biopsy:
  • Follicular dendritic cell sarcoma, completely excised (see comment)
  • Comment: Lymph node architecture is partially effaced by an abnormal population of epithelioid to spindle shaped cells in a whorling pattern. The neoplastic cells have ovoid nuclei, delicate chromatin, small nucleoli and abundant eosinophilic cytoplasm. They are variably admixed with small lymphocytes. Immunohistochemical stains were performed on paraffin sections of the left neck lymph node (CD21, CD23, CD31, CD34, CD35, CD45, clusterin, CXCL13, epithelial membrane antigen, melanA, keratin (AE1 / AE3), HMB45, S100 and terminal deoxynucleotidyl transferase). The abnormal cells are positive for CD21, CD23, CD35, clusterin and CXCL13. There are small numbers of terminal deoxynucleotidyl transferase positive (TdT) cells mixed with the tumor. The neoplastic cells are negative for the other markers tested. Morphology and immunohistochemical stains indicate the diagnosis of follicular dendritic cell sarcoma.

• Interdigitating dendritic cell sarcoma
  • Histologically may be indistinguishable from follicular dendritic cell sarcoma and immunohistochemical studies are required for a definite diagnosis
  • Positive for S100, negative or focally positive for clusterin (Am J Surg Pathol 2004;28:988)
• Langerhans cell histiocytosis
  • Langerhans cells are oval and recognized by their grooved, folded or indented nuclei with fine chromatin, inconspicuous nucleoli and thin nuclear membrane with moderately abundant and slightly eosinophilic cytoplasm
  • Positive for CD1a and langerin
• Kaposi sarcoma
  • Atypical spindled cells form slit-like vascular spaces containing red blood cells
  • Positive for HHV8
• Spindle cell thymoma
  • Site involved is usually anterior mediastinum
  • Bland spindled cells with fascicular to whorling growth pattern
  • Positive for keratin (AE1 / AE3)
• Metastatic carcinoma
  • Usually epithelioid cells in sheets, clusters or single cells with marked nuclear atypia
  • Positive for keratin (AE1 / AE3)
• Metastatic melanoma
  • Variable cytology including epithelioid or spindled cells with nuclear atypia and prominent nucleoli; cytoplasm may contain brown pigment (melanin)
  • Positive for S100 and MelanA
• Inflammatory myofibroblastic tumor
  • Spindled myofibroblasts and fibroblasts with bland nuclei
  • Positive for ALK1
• Pleomorphic sarcoma
  • Pleomorphic cells with a spectrum of cytology and may include spindled, plasmacytoid, epithelioid or multinucleated forms
  • Negative for clusterin, CXCL13, CD21, CD23, CD35

An 88 year old man presented with significant snoring and increasing sleep apnea. Laryngoscopy revealed a pharyngeal mass. CT head and neck with IV contrast revealed a 6 cm enhancing mass in the right parapharyngeal space. An excisional biopsy was performed. Based on the immunophenotype, what is the diagnosis?

1. Follicular dendritic cell sarcoma
2. Interdigitating dendritic cell sarcoma
3. Langerhans cell sarcoma
4. Pleomorphic sarcoma

A. Follicular dendritic cell sarcoma

Comment here

Reference: Lymph nodes - not lymphoma - Follicular dendritic cell sarcoma (FDCS)

Which of the following immunostains is highly sensitive and specific for follicular dendritic cell tumor?

1. CD1a
2. Clusterin
3. Fascin
4. S100

B. Clusterin (Mod Pathol 2005;18:260)

Comment here

Reference: Lymph nodes - not lymphoma - Follicular dendritic cell sarcoma (FDCS)