Unusual Presentation of Follicular Dendritic Cell Sarcoma as a Cystic Neck Swelling

Nonlymphoid Hematopoietic Diseases Presenting in Bone, Soft Tissue, and Other Extranodal Sites

Context.—

Although rare in everyday practice, the initial presentation of hematopoietic neoplasms other than lymphoma in the musculoskeletal system and other extranodal sites can generate challenging diagnostic problems for surgical pathologists.

Objective.—

To review the morphologic and immunophenotypic features of various nonlymphoid hematopoietic diseases presenting at extranodal sites, with emphasis on the inherent diagnostic pitfalls and differential diagnoses of these entities to aid surgical pathologists in their accurate recognition.

Data Sources.—

Cases reviewed herein represent both in-house and consult cases seen at our institution between 2010 and 2021.

Conclusions.—

Entities that present in this way include myeloid neoplasms and histiocytic/dendritic cell neoplasms. These tumors commonly cause nonspecific symptoms, and their histologic appearance can overlap with a variety of benign neoplasms and reactive processes. This can lead to delay in diagnosis and intervention with potentially lifesaving therapy; thus, accurate and expedient recognition is of paramount importance.

Clinicopathological characteristics of extranodal follicular dendritic cell sarcoma: A report of two cases

Follicular dendritic cell sarcoma (FDCS) is an extremely rare tumor, which mainly originates from FDCs in the lymph nodes. Sometimes FDCS can arise from outside the lymph nodes due to the existence of acquired lymphoid tissue, which becomes the histological basis of the tumor. The diagnosis of FDCS, particularly extranodal FDCS, presents a challenge for pathologists and hematopathologists. The present study presents two cases of extranodal FDCS based on clinical features and histomorphology. Soft tissue of the chest wall was involved in case 1 and right tonsil tissue in case 2. Case 1 underwent surgery, and was in good health post-operatively. During the 5-month post-operative follow-up period, the patient was healthy in all respects. Case 2 received surgery combined with radiotherapy, and the follow-up data reported that the patient remained alive, without signs of recurrence or metastasis during the 4-month post-operative follow-up period. Additionally, a total of 102 cases of extranodal FDCS were retrieved from the literature, which were extracted and reviewed carefully. The rates of recurrence, metastasis and mortality were 14.63 (12/82), 17.07 (14/82) and 8.29% (15/82), respectively. The overall survival rates of the 102 cases, showing 2-year total survival rates, were 70%, the same with that of 5-year total survival rates. The 2-year tumor-free total survival rates were 68%, and the 5-year equivalents were 32%. Female patients had a poorer prognosis than male patients (P<0.05). Kaplan-Meier estimation presented no statistically significant differences between disease-free survival rates or overall survival rates and age, tumor size or treatment (P>0.05).