Follicular dendritic cell tumour/sarcoma: a commonly misdiagnosed tumour in the thorax

AIMS: Follicular dendritic cell sarcoma is a rare tumour reported to occur occasionally in association with the hyaline-vascular type of Castleman's disease (HVCD). Most cases arise in lymph nodes, although extranodal presentation is described. METHODS AND RESULTS: Clinical, radiological and histological characteristics, including diagnosis on pre-resection material, were assessed in seven intrathoracic cases from five males and two females with a median age of 38 years. Clinical symptoms were related to mass location, six cases presenting within central and/or posterior mediastinal compartments and one within the lungs. Positron emission tomography-computed tomography demonstrated marked fluoro-deoxy-glucose avidity and the prominent vessels traversing the lesions. Four of six cases (67%) were misdiagnosed initially. HVCD was present in three cases. Two cases with high mitotic rates recurred after resection. All were positive for at least one of the follicular dendritic cell markers (CD21, CD35 and CD23). Six of seven cases (86%) show cyclin D1 expression ranging from 5% to 90%. CONCLUSIONS: Follicular dendritic cell sarcoma is often misdiagnosed on biopsy and pathologists need to be aware of the tumour to request the relevant immunohistochemistry, especially in masses presenting in the central/posterior mediastinum with high vascularity and standardized uptake values. Background HVCD appears more common than previously thought

Biomarkers for site-specific response to neoadjuvant chemotherapy in epithelial ovarian cancer: relating MRI changes to tumour cell load and necrosis.

Background Diffusion-weighted magnetic resonance imaging (DW-MRI) potentially interrogates site-specific response to neoadjuvant chemotherapy (NAC) in epithelial ovarian cancer (EOC).Methods Participants with newly diagnosed EOC due for platinum-based chemotherapy and interval debulking surgery were recruited prospectively in a multicentre study (n = 47 participants). Apparent diffusion coefficient (ADC) and solid tumour volume (up to 10 lesions per participant) were obtained from DW-MRI before and after NAC (including double-baseline for repeatability assessment in n = 19). Anatomically matched lesions were analysed after surgical excision (65 lesions obtained from 25 participants). A trained algorithm determined tumour cell fraction, percentage tumour and percentage necrosis on histology. Whole-lesion post-NAC ADC and pre/post-NAC ADC changes were compared with histological metrics (residual tumour/necrosis) for each tumour site (ovarian, omental, peritoneal, lymph node).Results Tumour volume reduced at all sites after NAC. ADC increased between pre- and post-NAC measurements. Post-NAC ADC correlated negatively with tumour cell fraction. Pre/post-NAC changes in ADC correlated positively with percentage necrosis. Significant correlations were driven by peritoneal lesions.Conclusions Following NAC in EOC, the ADC (measured using DW-MRI) increases differentially at disease sites despite similar tumour shrinkage, making its utility site-specific. After NAC, ADC correlates negatively with tumour cell fraction; change in ADC correlates positively with percentage necrosis.Clinical trial registration ClinicalTrials.gov NCT01505829