Follicular dendritic cell tumour/sarcoma

Equivalent normal cell

Follicular dendritic cells have a dendritic morphology and bear desmosomes. They are CD21+/CD35+/CD1a-. They show low levels of lysosomal enzymes and play a key role in antigen presentation.

Epidemiology

Only 56 confirmed cases have been reported in the English language literature. 24 of these were extra-nodal. Sites included oral cavity, spleen, liver, peritoneum, peripancreatic region, tonsil, palate, pharynx and thyroid, lung¹, soft tissues, skin and breast. 10-20% of cases are associated with Castleman's disease, usually of the hyaline vascular type^2,3.

Histopathology

The neoplastic cells vary from spindle to oval. They form fascicles and whorls, in some cases resembling those seen in meningioma. Rarely, there may be fluid-filled spaces, some perivascular resembling those seen in thymoma. Limited numbers of small lymphocytes are present.

Features associated with a more aggressive course include coagulative necrosis, nuclear atypia and greater than 5 mitoses per 10 HPF.

Immunohistochemistry; see the immunohistochemical differentiation of histiocytic and dendritic cell neoplasms

The percentages below are summarised from the literature:

FDC-markers: at least one should be positive CD21 usually positive0, 11/132, 17/173, 1/14, 10/115, 2/26 CD35 usually positive0, 17/173, 1/14, 10/115, 2/26 CNA.42 2/122 others commonly positive CD23 usually positive0, 12/132 Nerve growth factor receptor usually positive0 desmoplakin usually positive0, 10/173 fascin usually positive0 HLA-DR usually positive0, 1/26 Vimentin usually positive2, 0/11, 5/95 variably positive EMA often positive0, 1/11, 4/102, 14/163, 2/26 S-100 variably positive0, 0/11, 7/122, 6/173, 5/95 CD68 (KP-1) occasionally positive0, 0/11, 8/132, 2/173 CD45 (LCA) occasionally positive0, 0/11, 3/132, 0/26 CD1a should be negative CD1a consistently negative0, 0/11, 0/112   lysozyme consistently negative0, 1/13 (minority of cells positive in one case)2 myeloid markers myeloperoxidase consistently negative0, 0/82 CD34 consistently negative0, 0/132 T-cell markers CD3 consistently negative0, 0/11, 0/132 B-cell markers CD20 occasionally positive0, 0/11, 3/13 (positivity of >75% of cells in two cases)2 CD79a consistently negative0, 0/72 others negative CD30 consistently negative0, 0/132 bcl-2 0/11 AE1/3 0/11 SMA 0/11 Desmin (D33) 0/11, 1/115 HMB-45 consistently negative0, 0/11 cytokeratins consistently negative0 Cam5.2 0/11

Ultrastructure

There are desmosomes and long villous cell processes but no complex junctions, cytoplasmic interdigitations or Birbeck granules.

Differential diagnosis

• Other histiocytic and dendritic cell neoplasms; see the immunohistochemical differentiation of histiocytic and dendritic cell neoplasms

• Fibroblastic reticulum cell sarcoma: expresses desmin, SMA and cytokeratins

• Inflammatory pseudotumour; expression of FDC cell markers is weak.

• myofibroblastic tumours; positive for muscle specific actin.

• lymphoepithelioma-like carcinoma

• malignant melanoma

• thymoma

• meningioma

• MFH

• GIST

Prognosis

This is a low grade sarcoma, with about half of cases recurring and 25% metastasising, with a low mortality (10-20%^0,2 of patients dying from sarcoma). Intra-abdominal tumours are associated with a more aggressive^3,6.

References

⁰World Health Organization Classification of Tumours, Tumours of the haematopoietic and lymphoid tissues, IARC Press 2001.

¹Shah, R. N., Ozden, O., Yeldandi, A., Peterson, L., Rao, S., Laskin, W. B. Follicular dendritic cell tumor presenting in the lung: a case report. Hum Pathol 2001;32:745-749.

²Pileri, S.A., Grogan, T.M., Harris, N.L., Banks, P., Campo, E., Chan, J.K., Favera, R.D., Delsol, G., De Wolf-Peeters, C., Falini, B., Gascoyne, R.D., Gaulard, P., Gatter, K.C., Isaacson, P.G., Jaffe, E.S., Kluin, P., Knowles, D.M., Mason, D.Y., Mori, S., Muller-Hermelink, H.K., Piris, M.A., Ralfkiaer, E., Stein, H., Su, I.J., Warnke, R.A. and Weiss, L.M. Tumours of histiocytes and accessory dendritic cells: an immunohistochemical approach to classification from the International Lymphoma Study Group based on 61 cases. Histopathology 2002;41:1-29.

³Chan, J.K., Fletcher, C.D., Nayler, S.J. and Cooper, K. Follicular dendritic cell sarcoma. Clinicopathologic analysis of 17 cases suggesting a malignant potential higher than currently recognized. Cancer 1997;79:294-313.

⁴Moriki, T., Takahashi, T., Wada, M., Ueda, S., Ichien, M., Yamane, T. and Hara, H. Follicular dendritic cell tumor of the mesentery. Pathol Res Pract 1997;193:629-39.

⁵Perez-Ordonez, B., Erlandson, R.A. and Rosai, J. Follicular dendritic cell tumor: report of 13 additional cases of a distinctive entity. Am J Surg Pathol 1996;20:944-55.

⁶Hollowood, K., Stamp, G., Zouvani, I. and Fletcher, C.D. Extranodal follicular dendritic cell sarcoma of the gastrointestinal tract. Morphologic, immunohistochemical and ultrastructural analysis of two cases. Am J Clin Pathol 1995;103:90-7.

This page last revised 24.12.2002.

©SMUHT/PW Bishop