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 type2,3.

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:

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 aggressive3,6.

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