Primary Calvarial Lymphoma: A Case Report

Calvarial lymphoma is radiologically similar in many respects to meningiomas, solid fibrous tumours, osteomyelitis, and metastatic carcinomas. Even though it is an extremely rare phenomenon, the initial suspicion and detection of calvarial lymphoma are paramount to establishing a correct diagnosis which helps to determine an appropriate management strategy. We present an illustrative rare case of primary calvarial lymphoma along with a literature review focusing on the best management strategy for this rare entity. A 45-year-old female presented to our center in March 2022. She had a history of forehead swelling, which was progressively increasing in size over time. The metastatic workup and bone marrow biopsy were negative. Initially, extensive surgery was planned to resect the lesion, but after a discussion with the multidisciplinary team, a biopsy of the lesion was taken, which revealed a large B-cell lymphoma. It is prudent to consider calvarial lymphoma in the differential diagnosis of a progressively growing skull lesion, which may obviate the need for large resective surgery. A biopsy plus chemoradiation may be all that is required.

Differential gene expression in the calvarial and cortical bone of juvenile female mice

Introduction

Both the calvarial and the cortical bones develop through intramembranous ossification, yet they have very different structures and functions. The calvaria enables the rapid while protected growth of the brain, whereas the cortical bone takes part in locomotion. Both types of bones undergo extensive modeling during embryonic and post-natal growth, while bone remodeling is the most dominant process in adults. Their shared formation mechanism and their highly distinct functions raise the fundamental question of how similar or diverse the molecular pathways that act in each bone type are.

Methods

To answer this question, we aimed to compare the transcriptomes of calvaria and cortices from 21-day old mice by bulk RNA-Seq analysis.

Results

The results revealed clear differences in expression levels of genes related to bone pathologies, craniosynostosis, mechanical loading and bone-relevant signaling pathways like WNT and IHH, emphasizing the functional differences between these bones. We further discussed the less expected candidate genes and gene sets in the context of bone. Finally, we compared differences between juvenile and mature bone, highlighting commonalities and dissimilarities of gene expression between calvaria and cortices during post-natal bone growth and adult bone remodeling.

Discussion

Altogether, this study revealed significant differences between the transcriptome of calvaria and cortical bones in juvenile female mice, highlighting the most important pathway mediators for the development and function of two different bone types that originate both through intramembranous ossification.

Calvarial hyperostosis syndrome in a Dalmatian dog

Key Clinical Message

Calvarial hyperostosis syndrome is an uncommon and self-limiting disease affecting juvenile dogs. Only symptomatic treatment has been described, and diagnosis is based on clinical findings, imaging, and disease progression.

Abstract

This is the first reported case of calvarial hyperostosis syndrome in a Dalmatian dog. It is an uncommon osteoproliferative disease with diagnosis frequently based on clinical signs, imaging findings, and disease progression, with only symptomatic treatment described. Case describes a 5-month-old Dalmatian dog presented with a facial mass and difficulty eating. After imaging, mass was observed to be osteoproliferative, nonaggressive, and without affection of the temporomandibular joints and mandibles. Histology revealed an osseous-cartilaginous and proliferative lesion, together with scant amount of neutrophiles. Clinical improvement was observed after symptomatic treatment, and moderate lesion regression was observed in a CT reevaluation 6 months later.

Characterizing the role of Pdgfra in calvarial development

BACKGROUND

Mammalian calvarium is composed of flat bones developed from two origins, neural crest, and mesoderm. Cells from both origins exhibit similar behavior but express distinct transcriptomes. It is intriguing to ask whether genes shared by both origins play similar or distinct roles in development. In the present study, we have examined the role of Pdgfra, which is expressed in both neural crest and mesoderm, in specific lineages during calvarial development.

RESULTS

We found that in calvarial progenitor cells, Pdgfra is needed to maintain normal proliferation and migration of neural crest cells but only proliferation of mesoderm cells. Later in calvarial osteoblasts, we found that Pdgfra is necessary for both proliferation and differentiation of neural crest-derived cells, but not for differentiation of mesoderm-derived cells. We also examined the potential interaction between Pdgfra and other signaling pathway involved in calvarial osteoblasts but did not identify significant alteration of Wnt or Hh signaling activity in Pdgfra genetic models.

CONCLUSIONS

Pdgfra is required for normal calvarial development in both neural crest cells and mesoderm cells, but these lineages exhibit distinct responses to alteration of Pdgfra activity.

Varied Clinical Presentation and Management of Calvarial Metastases

Calvarium and skull base can be affected by a variety of benign, tumor-like, and malignant processes. Skull metastases (SMs) may be located in any layer of the skull and may be incidental or present with neurological symptoms during the diagnostic workup. In the present study, we discuss the occurrence of SMs from various index malignancies and their myriad clinical presentation. This data-based study includes patients of bone metastases between June 2018 and July 2020. Patients with skull bone metastases were recognized, and location of primary site, their clinical presentation, and management strategy were noted. Ten patients with skull bone metastases were identified during this period. Four patients had skull base location with clinical manifestation as syndromes. Six patients had primary from breast cancer, three from Ewing's sarcoma, and one from lung cancer. Management varied according to the primary site and symptoms of each patient. SM, though not rare, is often diagnosed incidentally but presents diagnostic and management challenges in the patient with cancer.

Canine Mesenchymal Stromal Cell-Mediated Bone Regeneration is Enhanced in the Presence of Sub-Therapeutic Concentrations of BMP-2 in a Murine Calvarial Defect Model

Novel bone regeneration strategies often show promise in rodent models yet are unable to successfully translate to clinical therapy. Sheep, goats, and dogs are used as translational models in preparation for human clinical trials. While human MSCs (hMSCs) undergo osteogenesis in response to well-defined protocols, canine MSCs (cMSCs) are more incompletely characterized. Prior work suggests that cMSCs require additional agonists such as IGF-1, NELL-1, or BMP-2 to undergo robust osteogenic differentiation in vitro. When compared directly to hMSCs, cMSCs perform poorly in vivo. Thus, from both mechanistic and clinical perspectives, cMSC and hMSC-mediated bone regeneration may differ. The objectives of this study were twofold. The first was to determine if previous in vitro findings regarding cMSC osteogenesis were substantiated in vivo using an established murine calvarial defect model. The second was to assess in vitro ALP activity and endogenous BMP-2 gene expression in both canine and human MSCs. Calvarial defects (4 mm) were treated with cMSCs, sub-therapeutic BMP-2, or the combination of cMSCs and sub-therapeutic BMP-2. At 28 days, while there was increased healing in defects treated with cMSCs, defects treated with cMSCs and BMP-2 exhibited the greatest degree of bone healing as determined by quantitative μCT and histology. Using species-specific qPCR, cMSCs were not detected in relevant numbers 10 days after implantation, suggesting that bone healing was mediated by anabolic cMSC or ECM-driven cues and not via engraftment of cMSCs. In support of this finding, defects treated with cMSC + BMP-2 exhibited robust deposition of Collagens I, III, and VI using immunofluorescence. Importantly, cMSCs exhibited minimal ALP activity unless cultured in the presence of BMP-2 and did not express endogenous canine BMP-2 under any condition. In contrast, human MSCs exhibited robust ALP activity in all conditions and expressed human BMP-2 when cultured in control and osteoinduction media. This is the first in vivo study in support of previous in vitro findings regarding cMSC osteogenesis, namely that cMSCs require additional agonists to initiate robust osteogenesis. These findings are highly relevant to translational cell-based bone healing studies and represent an important finding for the field of canine MSC-mediated bone regeneration.

An Evolutionary Conserved Signaling Network Between Mouse and Human Underlies the Differential Osteoskeletal Potential of Frontal and Parietal Calvarial Bones

The mammalian calvarial vault is an ancient and highly conserved structure among species, however, the mechanisms governing osteogenesis of the calvarial vault and how they might be conserved across mammalian species remain unclear. The aim of this study was to determine if regional differences in osteogenic potential of the calvarial vault, first described in mice, extend to humans. We derived human frontal and parietal osteoblasts from fetal calvarial tissue, demonstrating enhanced osteogenic potential both in vitro and in vivo of human frontal derived osteoblasts compared to parietal derived osteoblasts. Furthermore, we found shared differential signaling patterns in the canonical WNT, TGF-β, BMP, and FGF pathways previously described in the mouse to govern these regional differences in osteogenic potential. Taken together, our findings unveil evolutionary conserved similarities both at functional and molecular level between the mouse and human calvarial bones, providing further support that studies employing mouse models, are suitable for translational studies to human.

Craniofacial Chondromyxoid Fibromas: A Systematic Review and Analysis Based on Anatomic Locations

BACKGROUND

Craniofacial chondromyxoid fibromas (CMF) are a rare benign tumor of cartilaginous origin. They are commonly misdiagnosed due to the paucity of information on tumor characteristics. We performed a systematic review to characterize CMF located in different regions of the craniofacial skeleton.

METHODS

A search of the literature was executed using the search phrase "chondromyxoid fibroma" and included articles from 1990 - 2020. Sixty-eight articles met the inclusion criteria, with a total of 91 patients with analyzable data (22 with calvarial and 69 with sinonasal tumor locations). Descriptive analyses were performed to compare pre-selected characteristics between the two groups.

RESULTS

Sinonasal CMF frequently presented with cranial nerve palsy and expectedly had a high rate of nasal symptoms. Calvarial tumors frequently presented with an external mass and headache. Gross total resection (GTR) was achieved in a higher proportion of cases in the calvarial group versus the sinonasal group (83.3% vs 53.1%). Overall recurrence rate at 17.7% was higher in sinonasal CMF compared to the calvarial tumors at 8.3%. Recurrences after GTR were similar in the sinonasal and calvarial groups (9.7% vs 9.1%). In patients who did not achieve GTR, recurrence was higher in the sinonasal compared to the calvarial group (27.6% vs 0%).

CONCLUSION

Craniofacial CMF in calvarial and sinonasal locations have distinct clinical characteristics and response to treatment. Sinonasal lesions tend to have higher recurrence compared to calvarial CMF. Performance of GTR is associated with decreased recurrence in all CMF.

Calvarial Lesions: A Tertiary Centre's Experience Over Fifteen Years

Background

The human calvaria harbors a variety of pathology and majority of them are incidentally noticed as painless swelling. The aim of the present study is to describe the histopathological subtypes of calvarial lesions, their management and factors affecting their surgical outcome at a tertiary care referral center.

Material and Methods

All patients who underwent excision of the calvarial lesions over the last 15 years (from January 2005 to July 2019) were included in this study. Patients having calvarial pathology of infective origin and recurrent lesions were excluded. Any patient with multiple calvarial lesions who have been operated more than one time for same histopathological diagnosis was counted as one patient. We studied Karnofsky Performance Status (KPS) scores and radiological changes at 3-month follow up.

Results

Total 65 patients were recruited in this retrospective observational study. The median age of patients in the study was 29 years (range: 8 years to 68 years). Fibrous dysplasia 20 (30.7%) was the commonest lesion while metastatic thyroid carcinoma 3 (4.6%) was the most common malignant pathology. Complete excision was performed in 51 (78.5%) of patients while in 14 (21.5%) cases, subtotal or near total decompression were achieved. After three months of surgery, there was significant improvement in the KPS score (P < 0.00001). Duration of follow up ranges from 6 months to 5 years with 4 mortality in the study.

Conclusions

Most of the calvarial tumors were benign and surgically addressable. The malignant lesions were scattered with diverse underlying pathology and required individualized holistic approach.

A Rare Case of Diffuse Neurofibroma of the Scalp With Destructive Lesions Involving the Base of the Skull in a Patient With Neurofibromatosis Type 1

Diffuse neurofibroma is a benign tumor of peripheral nerves. Ten percent of neurofibromatosis type 1 (NF-1) patients can develop diffuse neurofibroma. Here, we report a case of diffuse neurofibroma involving the base of the skull in a 50-years-old patient with NF-1. The patient presented with diffuse involvement of the scalp with soft and mobile masses. Radiological investigations revealed skull bone lesions. Aggressive osteolytic lesions involving the base of the skull were present. Surgical excision with the repairing of the defects was suggested but the patient refused the treatment. The diagnosis of calvarial defects in diffuse neurofibroma is challenging. Early diagnosis can help in better management of the patients.

Successful Treatment of Anal Canal Cancer Metastasis to the Cranial Bones: A Case Report and Literature Review

Single metastasis to the cranial bone represents a very uncommon occurrence that can arise from an anal canal cancer. No cases of cranial bone metastasis from anal canal carcinoma are available in the literature. Herein, we present a case of a unique metastatic lesion to the right parietal bone that occurred after curative chemoradiotherapy of primary squamous cell anal canal carcinoma. The patient received radiotherapy and systemic platinum-based chemotherapy, with optimal local control, high compliance and a well tolerable level of toxicity.

Computer-guided calvarial mono-cortical bone blocks harvest: A novel approach for three-dimensional alveolar reconstruction of atrophic maxilla

BACKGROUND

Calvarial bone grafts have been one of the grafting options that provides predictable results for three-dimensional reconstruction of severely atrophied ridges owing to their low resorption and rapid revascularization, thus providing adequate volume for implant insertion. The aim of this study was to introduce a computer-guided technique for calvarial graft harvest to minimize the complications known with grafting from this donor site.

MATERIALS AND METHODS

Eight patients, suffering from severely atrophied, completely edentulous maxillary ridges, with an age range (21-30 years) were operated on (six males and two females). A custom-made guide for each patient based on preoperative computed tomography (CT) was fabricated for harvesting the outer table cortical bone blocks from the parietal bone, then particulate bone was collected with an auto-chip maker. Bilateral sinus lifting was indicated in all cases. The bone blocks were fixed intraorally and the bone particulates filled the gaps and the volume created by sinus lifting, then the whole complex was covered with collagen membranes fixed with titanium tacks. Immediate and 6 months CT were requested for evaluation of the guide accuracy and the graft integration, respectively.

RESULTS

In all cases, the guide was found to accurately fit into its preplanned position and to correctly locate the anticipated harvest site with the needed dimensions of the bone blocks. No intraoperative complications were encountered such as breakage through the inner table or cerebrospinal fluid leakage. Postoperatively, all the cases showed uneventual healing except one case that had an anterior dehiscence.

CONCLUSION

The computer-guided calvarial bone blocks harvest from the parietal bone is safe and predictable technique for three-dimensional reconstruction of severely atrophic edentulous maxilla.

Calvarial and skull base metastases: expanding the clinical utility of Gamma Knife surgery

OBJECT

Traditionally, the treatment of choice for patients with metastases to the calvaria or skull base has been conventional radiation therapy. Because patients with systemic malignancies are also at risk for intracranial metastases, the utility of Gamma Knife surgery (GKS) for these patients has been explored to reduce excess radiation exposure to the perilesional brain parenchyma. The purpose of this study was to report the efficacy of GKS for the treatment of calvarial metastases and skull base lesions.

METHODS

The authors performed a retrospective chart review of 21 patients with at least 1 calvarial or skull base metastatic lesion treated with GKS during 2001-2013. For 7 calvarial lesions, a novel technique, in which a bolus was placed over the treatment site, was used. For determination of local control or disease progression, radiation therapy data were examined and posttreatment MR images and oncology records were reviewed. Survival times from the date of procedure were estimated by using Kaplan-Meier analyses.

RESULTS

The median patient age at treatment was 57 years (range 29-84 years). A total of 19 (90%) patients received treatment for single lesions, 1 patient received treatment for 3 lesions, and 1 patient received treatment for 4 lesions. The most common primary tumor was breast cancer (24% of patients). Per lesion, the median clinical and radiographic follow-up times were 10.3 months (range 0-71.9 months) and 7.1 months (range 0-61.3 months), respectively. Of the 26 lesions analyzed, 14 (54%) were located in calvarial bones and 12 (46%) were located in the skull base. The median lesion volume was 5.3 cm(3) (range 0.3-55.6 cm(3)), and the median prescription margin dose was 15 Gy (range 13-24 Gy). The median overall survival time for all patients was 35.9 months, and the 1-year local control rate was 88.9% (95% CI 74.4%-100%). Local control rates did not differ between lesions treated with the bolus technique and those treated with traditional methods or between calvarial lesions and skull base lesions (p > 0.05). Of the 3 patients for whom local treatment failed, 1 patient received no further treatment and 2 patients responded to salvage chemotherapy. Subsequent brain parenchymal metastases developed in 2 patients, who then underwent GKS.

CONCLUSIONS

GKS is an effective treatment modality for patients with metastases to the calvarial bones or skull base. For patients with superficial calvarial lesions, a novel approach with bolus application resulted in excellent rates of local control. GKS provides an effective therapeutic alternative to conventional radiation therapy and should be considered for patients at risk for calvarial metastases and brain parenchymal metastases.