Follicular dendritic cell sarcoma of the pharyngeal region

Abstract

Follicular dendritic cell sarcoma (FDCS) is a rare neoplasm arising most commonly from follicular dendritic cells in the lymph nodes. It is exceedingly rare in extranodal sites, particularly in the pharyngeal region. The present study reports 3 cases occurring in the pharyngeal region. Case 1 had tonsil and cervical lymph node involvement, while case 3 also had tonsil involvement. Cases 1 and 3 relapsed locally at 3 and 17 months after surgery, respectively. Case 2 was diagnosed with a tumor in the parapharyngeal space and the patient succumbed to the disease 5 months after treatment with combined surgery and chemotherapy. All 3 cases were misdiagnosed initially. Pathological biopsy examination, including histopathology and immunohistochemistry, was essential for diagnosis. The data for 52 cases, including cases from the literature and the present cases, were analyzed. The results indicated that 57% (26/46) of the initial diagnoses were inaccurate, while the recurrence, metastasis and mortality rates were 40, 16 and 10%, respectively. The statistics supported the theory that FDCS of the pharyngeal region is a low-grade sarcoma. Involvement of the tonsils (52%, 27/52) and parapharyngeal space (19%, 10/52) were observed most commonly, while FDCS at various sites showed different prognoses. The various survival rates were calculated in the present study. The large tumors (≥4 cm) had a poorer prognosis than the small tumors (<4 cm; P<0.05). Among the 50 cases with available follow-up data, 46% (23/50) were treated with surgery alone, 52% (26/50) with combination therapy (surgery followed by chemotherapy and/or radiotherapy) and 2% (1/50) with surveillance. There was no statistically significant evidence (P>0.05) that combination therapy improves survival rates, compared with surgery alone.

Keywords: chemotherapy; follicular dendritic cell sarcoma; immunohistochemistry; pharyngeal; radiotherapy; surgery.

Figure 1

Pathological characteristics of pharyngeal FDCS. (A) Tumor cells arranged in a diffusing sheet-like distribution, partially in the storiform pattern (case 2). (B) Tumor cells arranged in the whorl pattern (case 3). (C) Indistinct cell borders and slightly eosinophil-stained cytoplasm of tumor cells. Infiltrating small lymphocytes and tissue cells were observed in the background (case 3). (D) Nuclei of tumor cells were irregular, round- or spindle-shaped, containing delicate chromatin and small nucleoli. Clear mitotic counts were observed (case 1). (E) Tumor cells were positive for podoplanin (case 3). (F) Tumor cells were negative for LCA, but the lymphocytes scattered in the background were positive for LCA (case 3). FDCS, follicular dendritic cell sarcoma; LCA, leukocyte common antigen.

Figure 2

OS curves of pharyngeal FDCS at various sites. OS, overall survival; FDCS, follicular dendritic cell sarcoma.

Figure 3

DFS curves of pharyngeal FDCS at various sites. DFS, disease-free survival; FDCS, follicular dendritic cell sarcoma.

Figure 4

Survival curves of pharyngeal FDCS. (A) OS and (B) DFS curves of pharyngeal FDCS. (C) OS and (D) DFS curves of FDCS with various sizes (<4 cm or ≥4 cm in the longitudinal dimension). (E) OS and (F) DFS curves of FDCS with various treatments (surgery alone or surgery followed by RT and/or ChT). FDCS, follicular dendritic cell sarcoma; OS, overall survival; DFS, disease-free survival; RT, radiotherapy; ChT, chemotherapy.