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K. Vroobel
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P3.08 - Poster Session/ Thymoma, Mesothelioma and Other Thoracic Malignancies (ID 226)
- Event: WCLC 2015
- Type: Poster
- Track: Thymoma, Mesothelioma and Other Thoracic Malignancies
- Presentations: 1
- Moderators:
- Coordinates: 9/09/2015, 09:30 - 17:00, Exhibit Hall (Hall B+C)
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P3.08-020 - Clinicopathological Features of Primary Intra-Thoracic Follicular Dendritic Cell Sarcomas (ID 2869)
09:30 - 09:30 | Author(s): K. Vroobel
- Abstract
Background:
Follicular dendritic cell sarcoma (FDCS) is defined in the WHO as a neoplastic proliferation of spindle/ovoid cells with morphological and immunohistochemical features of follicular dendritic cells. It is a rare tumour with no clear aetiology, often misdiagnosed and difficult to characterise. Occasionally it occurs in association with the hyaline-vascular type of Castleman disease which, in such cases, is considered its precursor lesion. Most cases are reported in lymph nodes, however several cases with extranodal presentation have been described. Despite the fact that metastasis are common in the lung, only 7 cases have been reported as primary pulmonary FDCS. Surgical excision with chemotherapy is the treatment of choice giving transient, partial response in some cases. We report our experience within the last 15 years of 6 cases of FDCS arising in the mediastinum and in the lung.
Methods:
The study included 7 patients referred to Royal Brompton Hospital between 2001 and 2014 with a diagnosis of FDCS. Criteria for inclusion were morphological and immunohistochemical: fascicles/whorls of spindle to ovid cells with features resambling follicular dendritic cells and the expression of one or more specific markers (CD21, CD23 and CD35). We performed a broad immunohistochemical panel and we looked for the presence of Castleman’s disease and the type of inflammatory infiltrate in the background. Clinical information were obtained from hospital records and clinicians.
Results:
After review, we identified 6 cases consistent with the diagnosis of FDCS, four males and two females between 25 and 61 years old. One case was excluded because of equivocal expression of specific markers. Three patients presented with a mediastinal mass and one having two recurrences within the study period. Two patients presented with a lung mass and one with a radiological pleurally based mass infiltrating the lung and chest wall. Clinical presentation was mainly with cough and chest pain due to the location of the tumour.Histologically all cases showed an atypical spindle cell proliferation with storiform pattern within a mixed inflammatory stroma. Mitotic rate was generally low except in case of recurrences. In three cases Castleman’s features were present in the background.Five out 6 cases (83.3%) expressed CD21, CD35, p53 and cyclin D1, 3 cases (50%) expressed CD35, S100, lysozyme and bcl2 and 2 cases (33.3%) expressed KP1, PGM1, CD45, CD4, CD30 and bcl6. All were negative for keratins. Four cases (66.7%) were initially misdiagnosed as pleomorphic malignant tumour.Background showed a variably amount of B and T cells, with T cells expressing CD4 and PD1. Follow up data were available for 4 patients: one died after 5 years, 2 were alive with no recurrence after one year and one is alive after 8 years and two recurrences.
Conclusion:
FDCS is a rare tumour and should be considered in cases with a malingant spindle cells proliferation negative for the most common markers. Our series also showed Cyclin D1 expression in this tumour which has not previously been reported. This may raise the possibility for a new more effective therapeutic approach but further studies are needed.
