Author: Singer, Adam D; Weinberger, Paul M; Seybt, Melanie W; Jackson, Lana L; Teague, Daniel J; Figueroa, Ramon E
Date published: July 1, 2010
Follicular dendritic cell sarcoma (FDCS) is a rare neoplasm that was first described in 1986 by Monda et al.1 It arises from the antigen-presenting dendritic cells found in the reticuloendothelial system.2 FDCS generally presents as a slowly growing, painless mass.3 Approximately two-thirds of all cases of FDCS arise from -the lymph nodes of the head and neck; the remainder arise from extranodal tissue within the axilla, gastrointestinal tract, spleen, liver, and oral cavity.4
A 60-year-old man presented to our otolaryngology clinic with a right-sided neck mass. He was in no acute distress, and he had no difficulty breathing. Palpation of the neck revealed a nontender, 9 × 6-cm mass occupying most of the right side of the neck.
Contrast-enhanced computed tomography (CT) of the neck showed the mass along the anterior cervical lymph node chain. It measured 7.4 × 7.8 × 6.5 cm in orthogonal dimensions, and it extended from C2 to C6. The mass demonstrated mildly heterogeneous internal enhancement, and it contained internal lobular areas of subtle low density without any internal calcifications (figure 1, A and B). Despite its size, this lesion had a well-defined capsule. No inflammatory reaction in the adjacent fat was apparent. Mild pressure remodeling of the inferior cortical margin of the right mandible was appreciated on bone window detail (figure 1, C). Adjacent neck structures were displaced but not invaded. No other neck mass or lymphadenopathy was observed.
Initially, the patient preferred a strategy of watchful waiting. When the mass enlarged to 12 × 8 cm over the next 6 months, he was motivated to proceed with surgical excision. At surgery, a 13 × 8-cm cystic mass was found to be arising from the submandibular compartment of the right parapharyngeal space. The mass had displaced the carotid bifurcation medially and compressed the internal jugular vein posteriorly, and it peeled off the mandible easily.
On pathologic examination, the resected specimen was described grossly as a tan, multicystic mass. The overall histologic architecture was fascicular with a whorled, storiform pattern focally (figure 2). Extensive hemorrhage was present. The neoplastic cells were spindle-shaped and featured mildly pleomorphic, convoluted nuclei. Some of the cells contained clumped chromatin. The cytoplasm within the neoplastic cells was eosinophilic, and there was a moderately increased nucleus-to-cytoplasm ratio. Few perivascular inflammatory cells were present.
Immunohistochemistry revealed that the spindle cells were positive for CD21, CD68, and vimentin and weakly positive for S-IOO. The spindle cells were negative for melanin A, HMB-45, epithelial membrane antigen, pankeratin, muscle actin, CDl 17, low-molecular-weight keratin, high-molecular-weight keratin, CD34, CD5, factor Villa, and CD45/leukocyte common antigen.
In view of the low incidence of FDCS and the relatively recent first description of this neoplasm, there is a paucity of information regarding its imaging characterization.2,3,5,6 Previous CT studies have found contrast enhancement,2·7'8 and one case report included a finding of calcification.6 In our case, CT with contrast demonstrated a large, mildly enhancing, encapsulated, heterogeneous mass in the inferior right parapharyngeal space that had compressed nearby structures but had not invaded them. No other lymphatic tissue appeared to be involved, and no calcification was appreciated.
In addition to FDCS, the differential diagnosis for a large, relatively asymptomatic neck mass in an adult should include lymphoma, schwannoma, glomus tumor, lymphatic spread of thyroid cancer, head or neck squamous cell carcinoma, and infection. In view of the broad nature of this differential diagnosis, immunohistochemistry is often required to establish the diagnosis. A suspicion of FDCS should be raised in a patient who presents with a bulky, slowly growing, unilateral suprahyoid or infrahyoid mass that is contained within the lymphatic tissue and has a heterogeneous appearance on contrast-enhanced CT. A biopsy with immunohistochemistry for diagnosis is recommended.
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Adam D. Singer, BS; Paul M. Weinberger, MD; Melanie W. Seybt, MD; Lana L. Jackson, MD; Daniel J. Teague, MD; Ramon E. Figueroa, MD, FACR
From the Department of Radiology ( Mt. Singer and Dr. Figueroa) , the Department of Otolaryngology ( Dt. Weinberger, Dr. Seybt, and Dr. Jackson), and the Department of Pathology (Dr. Teague), the Medical College of Georgia, Augusta.