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Aims The increasing use of highly conformal radiation techniques to treat meningioma confers a greater need for accurate targeting. Several groups have shown that positron emission tomography/computed tomography (PET/CT) information alters meningioma targets contoured by single observers, but whether this translates into improved accuracy has not been defined. As magnetic resonance imaging (MRI) is the cornerstone of meningioma target contouring, simultaneous PET/MRI may be superior to PET/CT. We assessed whether 68 Ga DOTATATE PET imaging (from PET/CT and PET/MRI) reduced interobserver variability (IOV) in meningioma target volume contouring. Materials and methods Ten patients with meningioma underwent simultaneous 68 Ga DOTATATE PET/MRI followed by PET/CT. They were selected as it was anticipated that target volume definition in their cases would be particularly challenging. Three radiation oncologists contoured target volumes according to an agreed protocol: gross tumour volume (GTV) and clinical target volume (CTV) on CT/MRI alone, CT/MRI+PET(CT) and CT/MRI+PET(MRI). GTV/CTV Kouwenhoven conformity levels (KCL), regions of contour variation and qualitative differences between PET(CT) and PET(MRI) were evaluated. Results There was substantial IOV in contouring. GTV mean KCL: CT/MRI 0.34, CT/MRI+PET(CT) 0.38, CT/MRI+PET(MRI) 0.39 ( P = 0.06). CTV mean KCL: CT/MRI 0.31, CT/MRI+PET(CT) 0.35, CT/MRI+PET(MRI) 0.35 ( P = 0.04 for all groups; P > 0.05 for individual pairs). One observer consistently contoured largest and one smallest. Observers rarely decreased volumes in relation to PET. Most IOV occurred in bone followed by dural tail, postoperative bed and venous sinuses. Tumour edges were qualitatively clearer on PET(MRI) versus PET(CT), but this did not affect contouring. Conclusion IOV in contouring challenging meningioma cases was large and only slightly improved with the addition of 68 Ga DOTATATE PET. Simultaneous PET/MRI for meningioma contouring is feasible, but did not improve IOV versus PET/CT. Whether volumes can be safely reduced according to PET requires evaluation.

The treatment of primary brain tumours remains a significant clinical challenge and developing novel treatment approaches is a major unmet need. The results from recent studies investigating novel molecular targeting agents have been disappointing and this is thought to reflect significant intra-tumoral heterogeneity, tumour cell plasticity and redundancy in targetable pathways. Improved understanding of the underlying biology that drives hallmarks of this disease including angiogenesis, invasion and stem-like behaviour is necessary to identify new approaches to intervention. The identification of prognostic and predictive biomarkers that reflect this biology is also an unmet need in progress towards individualised treatment.

We report the case of a 54-year-old man with primary central nervous system lymphoma (PCNSL) who achieved a radiological complete response to high-dose methotrexate and 6 months later had a simultaneous local and testicular relapse.

Lymphangioma circumscriptum is a rare disorder of lymphatic channels, the cause of which is poorly understood. It is an unpleasant, but benign, condition conventionally managed by wide local excision, which provides symptom control and often prevents recurrence. No long term complications and no association with squamous cell carcinoma have been previously documented. We present a 20-year-old patient with lymphangioma circumscriptum involving the vulval and perianal areas, which recurred after surgery and seems to have predisposed to squamous cell carcinoma 11 years after presentation.