Follicular dendritic cells emerge from ubiquitous perivascular precursors.

The differentiation of follicular dendritic cells (FDC) is essential to the remarkable microanatomic plasticity of lymphoid follicles. Here we show that FDC arise from ubiquitous perivascular precursors (preFDC) expressing platelet-derived growth factor receptor ß (PDGFRß). PDGFRß-Cre-driven reporter gene recombination resulted in FDC labeling, whereas conditional ablation of PDGFRß(+)-derived cells abolished FDC, indicating that FDC originate from PDGFRß(+) cells. Lymphotoxin-α-overexpressing prion protein (PrP)(+) kidneys developed PrP(+) FDC after transplantation into PrP(-) mice, confirming that preFDC exist outside lymphoid organs. Adipose tissue-derived PDGFRß(+) stromal-vascular cells responded to FDC maturation factors and, when transplanted into lymphotoxin ß receptor (LTßR)(-) kidney capsules, differentiated into Mfge8(+)CD21/35(+)FcγRIIß(+)PrP(+) FDC capable of trapping immune complexes and recruiting B cells. Spleens of lymphocyte-deficient mice contained perivascular PDGFRß(+) FDC precursors whose expansion required both lymphoid tissue inducer (LTi) cells and lymphotoxin. The ubiquity of preFDC and their strategic location at blood vessels may explain the de novo generation of organized lymphoid tissue at sites of lymphocytic inflammation.

Impact of ultra-low-field intraoperative magnetic resonance imaging on extent of resection and frequency of tumor recurrence in 104 surgically treated nonfunctioning pituitary adenomas.

OBJECTIVE: To analyze the impact of intraoperative ultra-low-field magnetic resonance imaging (MRI) on the extent of tumor resection in nonfunctioning pituitary adenomas (NFPAs). METHODS: Retrospective analysis was performed of 104 consecutive cases undergoing intraoperative MRI-guided transsphenoidal surgery for NFPA. General patient data; endocrinologic parameters; neurologic examinations; preoperative and postoperative symptoms; preoperative, intraoperative, and postoperative imaging; and proliferation index were evaluated with an overall mean follow-up of 34 months. RESULTS: The use of intraoperative MRI led to an increase of the overall remission rate by 52.2%, from 44.2% to 67.3%. Tumor characteristics such as size and invasiveness had an important impact on postoperative remission rate. In patients with macroadenoma and without previous pituitary surgery, a remission rate of 82.2% was achieved. Overall, the sensitivity of intraoperative MRI in the study was 32.4%. There were no false-positive interpretations. A higher proliferation index was found in the 15 patients with postoperative enlargement of residual adenomas or tumor recurrence compared with the other patients of the study group. CONCLUSIONS: This study shows that the outcome of surgical treatment of NFPAs was improved by the use of intraoperative MRI owing to more radical resection. The remission rate seems to depend on tumor characteristics. Recurrent disease might be reduced by the use of intraoperative MRI leading to more complete surgical resection of NFPAs.

Rare suprasellar glioblastoma: report of two cases and review of the literature.

BACKGROUND AND IMPORTANCE: The suprasellar and hypothalamic/chiasmatic regions can harbor a broad range of pathologic conditions, both neoplastic and nonneoplastic; however, malignant gliomas are extremely rare in those regions. CLINICAL PRESENTATIONS: Patient 1 was a 70 year-old man with weight loss and rapidly progressive visual impairment. A mass centered in the hypothalamus was detected on magnetic resonance (MR) imaging. The second patient, a 45 year-old woman, complained of visual symptoms and headaches. MR imaging revealed a combined intra- and suprasellar mass. In both instances, the preoperative differential diagnosis favored craniopharyngioma. Histological examination confirmed the diagnosis of glioblastoma. CONCLUSION: We report two rare adult cases of hypothalamic/chiasmatic glioblastoma. The authors review the literature, highlighting the importance of considering this rare entity in the differential diagnosis of suprasellar and hypothalamic lesions.

Current treatment options in dermatofibrosarcoma protuberans.

Dermatofibrosarcoma protuberans (DFSP) is a rare malignant dermal neoplasm characterized by slow infiltrative growth, little metastatic potential but a high tendency to recur locally after surgical excision. DFSP is associated with a high cure rate. The optimal therapy is complete surgical resection. The recurrence potential of DFSP is directly related to the extent of resection. The need for wide excision margins has been amply documented. Wide local excision is a frequently used practice. Mohs micrographic surgery with continuous histological margin control is further propagated to reduce local recurrence rates. In more than 90% of DFSP, a specific chromosomal aberration is described, involving Chromosomes 17 and 22. It leads to a constitutive activation of the platelet-derived growth factor receptor (PDGFR) followed by continuous stimulation of the tumor cell growth. The use of targeted inhibitors of PDGFR is a good therapeutic option in the treatment strategy of unresectable locally advanced, recurrent or metastatic disease. With Imatinib, a selective PDGFR tyrosin kinase inhibitor, partial and complete remissions of DFSP could be achieved. This article reviews the current opinion and literature about DFSP and resulting therapy strategies.

Remission with Imatinib mesylate treatment in a patient with initially unresectable dermatofibrosarcoma protuberans--a case report.

BACKGROUND: Dermatofibrosarcoma protuberans (DFSP) is a rare, malignant dermal mesenchymal neoplasm characterized by a slow, infiltrative growth. These neoplasms have a high tendency to recur locally after surgical excision. However, metastasizing cases are exceedingly rare. Cytogenetically, DFSP is characterized by a t(17;22)(22;q13) aberration with fusion of the COL1A1 gene on chromosome 17 with the PDGFB gene on chromosome 22. Here, we report on a successful treatment of a patient with a targeted therapy using the tyrosine kinase inhibitor Imatinib mesylate in neoadjuvant intention. PATIENTS AND METHODS: A patient with recurrent and initially unresectable but non-metastatic DFSP of the scalp received Imatinib over 3 months with increasing dosage from 400 mg/day to 800 mg/day orally. Due to the location of the DFSP in our patient, we intended to decrease tumor size preoperatively to allow complete surgical resection. Response to therapy was assessed by computed tomography. RESULTS: Preoperative treatment with Imatinib resulted in decrease of tumor size by over 60% in the greatest dimension during 3 months of therapy, enabling the complete resection of the DFSP by radical surgery with achieving an acceptable cosmetic result. Surgery was followed by adjuvant Imatinib therapy over 6 months. CONCLUSIONS: Imatinib mesylate is effective in neoadjuvant treatment of primary unresectable dermatofibrosarcoma protuberans and can be considered as a useful option in the therapy regimen.