[1388] Follicular Dendritic Cell Sarcoma Frequently Contains Intratumoral TdT-Positive T Cells That Are Associated with Paraneoplastic Autoimmune Multiorgan Syndrome (PAMS).

Matthew P Walters, Mark R Pittelkow, William R Macon, Paul J Kurtin, Karen L Grogg. Mayo Clinic, Rochester, MN

Background: Recently Kim et al. reported a mesenteric follicular dendritic cell sarcoma (FDCS) with an immature T cell proliferation, associated with paraneoplastic pemphigus and myasthenia gravis. (Hum Pathol 2010;41:129-133). Our goal was to determine how frequently immature T cells can be found in FDCS, and how often this is associated with autoimmune disease.
Design: 26 cases of FDCS were identified in our general practice and consultation files. Paraffin immunohistochemistry was performed to assess the lymphocyte population (TdT, CD1a, CD3, CD4, CD8, CD20) as well as the sarcoma (CD21, CD23, CD35, clusterin, CXCL13, podoplanin). Chart review was performed to chacterize the clinical behavior including evidence of autoimmune disease.
Results: Patients had an average age of 51.7 years (range 14-88), M:F ratio of 1.4:1. The tumors were positive for at least 2 of the following FDC markers: CD21 (73%), CD23 (62%), CD35 (64%), clusterin (100%), CXCL13 (88%) and podoplanin (81%). 11 of 26 (42%) contained immature CD3 positive T cells (4 numerous, 4 patchy, 3 focal) showing TdT positivity, and coexpression of CD1a in a subset (4 of 11). Average age in this subgroup of 11 patients was 50.8 years (range 26-88), M:F ratio of 2.7:1. The anatomic sites included axillary, cervical, mediastinal, retroperitoneal and perigastric lymph nodes, tonsil and retropharynx. In the numerous category, the TdT positive cells appeared to be CD1a+/CD4+/CD8+ (2 cases), CD1a-/CD4+/CD8+ (1 case) and CD1a+/CD4+/CD8- (1 case). In the other cases, the infiltrate contained a predominance of CD8 over CD4 positive cells, but the phenotype of immature T cells was difficult to determine. 3 of 4 patients with numerous immature T cells had associated autoimmune disease clinically categorized as paraneoplastic autoimmune multiorgan syndrome (PAMS), exhibiting at least two of the following: blisters/erosions in the oral cavity, lichenoid skin lesions, obliterative bronchiolitis, myasthenia gravis. Despite tumor resection, PAMS persisted in each patient.
Conclusions: The presence of TdT positive T cells is not uncommon in FDCS, occurring in 42% of cases in this series. When numerous, there is a strong association with PAMS, raising the possibility that the neoplasm recruits an immature T cell population and fosters development of autoreactive T cells that mediate subsequent autoimmunity. Recognition of the possibility of immature T cell proliferation in FDCS is important to avoid misinterpretation as thymoma or T lymphoblastic lymphoma.
Category: Hematopathology

Tuesday, March 1, 2011 11:15 AM

Platform Session: Section B, Tuesday Morning


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