Calvarial Lesions: A Tertiary Centre's Experience Over Fifteen Years
Correspondence Address: Source of Support: None, Conflict of Interest: None DOI: 10.4103/0028-3886.319236
Source of Support: None, Conflict of Interest: None
Keywords: Benign, calvarial, excision, malignant, swellingKey Message: The human skull acts as an incubator for various pathology with a wide spectrum of presentation, and amongst them the benign lesions are more frequent. The scalp swelling is the most common manifestation and a thorough evaluation is mandatory before definitive treatment of calvarial lesions.
The evidence of calvarial tumor dates back to fossilized skull in human mummies., The unique morphology of human skull provides a fertile ground for a variety of pathology to evolve. These lesions may arise from bone marrow due to hematogenous seedings of pathological cells. The scalp-based lesions involve the outer table while dural-based lesions invades the inner table of skull., Besides calvarial tumors a variety of traumatic, congenital, metabolic and infectious pathology of calvarium also contributes to the scalp swelling. Limited literature in the form of case reports or case series are available regarding calvarial tumors.,
The aim of this observational study is to share the experience of 65 surgically managed calvarial lesions between Jan 2005 to July 2019 and to describe the histopathological subtypes and the factors affecting their clinical outcome.
This observational study was conducted in the department of Neurosurgery, at a tertiary care referral hospital; and the study was approved by the institutional ethical committee (IEC). Written informed consent was obtained as per our departmental and institute protocol. The calvarial lesions were defined as the tumor involving the outer table or inner table and/or the lesions involving the Calvaria in whole thickness based on radiological and/or intraoperative findings. All patients who underwent excision of the calvarial lesion over the last 15 years (from January 2005 to July 2019) were included in this study.
Patients having calvarial lesions of infective pathology and recurrent lesions were excluded. Any patient with multiple calvarial lesions who have been operated more than one time with same histopathological diagnosis was counted as one patient in our study [Figure 1].
All the patients with scalp swelling were subjected to detailed clinical examination. It includes the evaluation of symptom complex associated with scalp swelling, presence of associated comorbidity, history of surgical intervention and Karnofsky Performance Status (KPS) score at the time of admission.
Targeted investigation in the form of contrast enhanced computed tomography (CECT) scan of head, describes the nature of calvarial lesion. The brilliant spatial resolution of CT scan helps it to differentiate between osteolytic and osteoblastic lesions. The contrast enhancement suggests the nature and vascularity of the mass. Magnetic resonance imaging (MRI) scan with gadolinium contrast describes about the lesion matrix. Magnetic resonance venography (MRV) was highly useful to describe the venous anatomy as well as patency of dural venous sinuses if the lesions were in the close proximity to the important venous complex.
Metastatic work up
Patients with metastatic lesion or suspected underlying malignancy were subjected to investigations in search of primary. This include high- resolution CT (HRCT) chest, ultrasound abdomen, CECT abdomen and pelvis along with radiology of extremities, if required. Positron emission tomography (PET) scan and isotope scan were kept as reserved diagnostic tools in case of occult primary.
Intra-arterial digital subtraction angiography (IADSA) and tumor embolization
Tumors with high vascularity, those crossing the midline and/or causing infiltration of dural venous sinus; were subjected to IADSA. Angiography was found to be diagnostic by delineating the major arterial feeders and draining veins as well as therapeutic by embolization of the major feeders. Tumors having external carotid artery as major blood supply, polyvinyl (PV) alcohol particles (size range: 300- 500 microns) were used as embolization material of choice. Those tumors with intradural extension having pial feeders were subjected to liquid embolic agents such as glue, onyx or coils. Metastatic calvarial lesions were subjected to neoadjuvant treatment in the form of chemotherapy and/or radiotherapy (RT), if needed.
Surgical strategy for maximal safe resection
The lesions which were close to major venous sinus underwent maximal safe resection by drilling or undercutting the bone overlying the sinus area. In the recent past, the flowable hemostatic material was also used intraoperatively to control sudden blood loss in case of lesions adjacent to dural venous sinuses.
The intraparenchymal extension was managed as per micro neurosurgical techniques. Close study of T2WI and contrast MRI were found to be mandatory in order to understand the pial breach and parenchymal extension of the lesion. Lesions with paranasal sinus, skull base and vascular sinus extension needs special attention because of their tendency to recur, if residual pathology exist.
Surgical Intervention and reconstruction
All included patients underwent elective surgery where excision of lesion was followed by calvarial defect reconstruction, if required. Patients with highly vascular calvarial tumor underwent acute normovolemic hemodilution (ANH) to decrease intraoperative blood loss. Before tumor decompression, the major feeders were ligated to mitigate their vascularity. Tumor extension, dural sinus invasion or intradural spread with involvement of eloquent brain areas often preclude complete tumor excision. Intraoperative squash cytology was sent routinely from most representative portion of the tumor. After decompression of intradural portion (if present), the dural closure was carried out with healthy pericranial fascia, fascia lata or artificial dura (collagen- based; bovine origin). Calvarial reconstruction was carried out by using patient specific titanium mesh cranioplasty. Autologous split thickness calvarial graft, acrylic and calcium phosphate were also used as construct material.
Patients requiring radiotherapy were subjected to external beam radiotherapy (EBRT) using 20 to 25 Gray in divided doses. Selected cases who fulfilled the criteria for chemotherapy were subjected to standard chemotherapy regimen (based on histological differentiation) as per discretion of the medical oncologist.
All patients were followed up at three months after surgery in outpatient department. The KPS score and post-operative clinico- radiological evaluation were performed during these visits. Obvious changes at the operative site, such as; presence of new onset swelling, skin discoloration over scalp or sensory motor deficits and surgical outcome in the form of new onset deficit were recorded.
Statistical analysis was done by using SPSS for window 19.0 (SPSS Inc. Chicago). The parametric data were expressed as Mean/Median and non-parametric data were expressed as number (n) and percentage. Parametric data were analyzed using t-test. While the categorical data were analyzed using chi- square test. The p- value <0.05 were considered significant.
The total of 65 operated and biopsy proven patients were recruited into the study; who received treatment over the last 15 years. Male to female ratio in our study was 1.4 :1. The median age of the patients in the study was 29 years (range: 8 years to 68 years). During postoperative period, five patient developed surgical site infection. No fresh onset neurological deficits nor any mortality were noticed at 3-month follow up.
Scalp swelling (77%) was the most common presenting complaint, followed by headache and vomiting [Table 1]. Altered mental status was present in two patients along with scalp swelling suggestive of brain parenchymal invasion and raised intracranial pressure. Grade 2 to 3 papilledema was present in 6 (9.2%) patients suggestive of secondary optic atrophy. Neurological deficit during evaluation was detected in 35 (53.8%) patients, either in isolation or as a part of symptom complex. Eight patients (12.3%) were found to have underlying primary malignancy in the form of thyroid, breast and lung cancer. The mean KPS score in preoperative period was 81.2 ± 8.9.
Pre-operative work up revealed frontal bone as most commonly involved bone [Table 1] and [Table 2] The tumor volume in pre-operative radiology was calculated by using 3D reconstruction in CECT head; mean volume 57.3 ± 56.8 cc. In benign and tumor like lesions, the mean volume was 44.1 ± 29.5 cc, while in malignant tumors the mean volume was 151.6 ± 104.8 cc [Table 3].
Evaluation of surgical intervention
The mean volume of blood loss in tumor excision was 475.3 ± 435.7 cc. During excision of benign and tumor like calvarial lesions, the mean volume of blood loss was 369.6 ± 205.7 cc and in case of malignant tumors the mean volume of blood loss was 1228.7 ± 811 cc. After tumor excision, titanium mesh cranioplasty was performed in 40 patients while 5 patients underwent split calvarial bone grafting for reconstruction. Ten out of sixty-five patients underwent interval cranioplasty after management of the primary pathology. The mean duration of hospital stay was 6.9 ± 2.3 days. Five patients had prolonged hospital stay due to cerebrospinal fluid (CSF) leak and wound infection.
At the 3-month follow up evaluation, there was significant improvement in 29 out of 35 patients (83%) who had visual, auditory and lobar signs before surgery. Thirty patients who were asymptomatic and intact remained so. The mean KPS score at 3-month follow up was 89.7 ± 6.1 (P < 0.00001). As compared to preoperative status, a significant improvement in KPS score was noticed amongst patients with benign and tumor like lesions (P < 0.00001) as well as those with malignant calvarial tumors (P < 0.0002) [Table 4].
Out of 65 patients, fifty-one underwent total excision while fourteen patients underwent subtotal decompression of the lesion. Subtotal excision was carried out in nine cases with non-separable dural sinus invasion and five cases with non resectable skull base extension.
In our study, at three months following surgery; the disease was stable and no recurrence was noticed in both the groups. Median follow up in partial excision was 22 months (range: 12 months to 60 months) while in case of complete excision, it was 16 months (range: 6 months to 55 months).
There were two recurrences in fibrous dysplasia due to involvement of frontal sinus and sphenoid sinus which becomes symptomatic in the form of headache, recurrent sinusitis, hyposmia and diminution of vision in addition to swelling over the operative site. These recurrences were noticed after two years of primary surgery. The recurrence involving frontal sinus was re-excised trans cranially and the recurrence with sphenoid sinus involvement underwent endoscopic decompression along with otorhinologist at our center.
Recurrence of fibrous dysplasia involving the temporal bone manifested as conductive hearing loss with intact seventh nerve function after three years of surgery. Over the period of five years of follow up, repeated excision for three times was performed in view of extensive mastoid air cells involvement.
Two cases, diagnosed as atypical meningioma and hemangioma with significant dural venous sinus involvement had partial excision. Recurrence was noticed in one case after 30 months of primary surgery and was again subjected to maximal safe resection.
A case of anaplastic meningioma, had recurrence after eighteen months of primary surgery, despite total excision. This represents the aggressive behavior of the tumor and microscopic spread of disease process beyond the defined boundary.
Total four patients died in the follow up period. Death occurred due to primary disease in case of metastatic calvarial tumors, undergone complete excision of lesion.
The cranial vault harbors a wide variety of lesions in a relatively small area. The encountered 13 benign and tumor like lesions along with five malignant pathologies justify the calvarium as a Pandora box, which caters as well as give rise to variety of tumors.
Benign and tumor like lesions
The incidence of primary neoplasms of skull vault is 0.8% of all the bone malignancy. The occurrence of benign lesion is more frequent than tumors arising de novo from the calvarium, although limited literature are available in support of this because of paucity of biopsy of all the skull lesions. The diagnostic possibilities of calvarial mass include congenital, neoplastic, inflammatory or traumatic etiology. Usually these lesions are noticed incidentally as painless swelling during clinical and radiological evaluation for other disease or unrelated symptom complex.,
In the present study, benign tumors contribute 27 (42%) cases while 30 (46%) cases were found to be tumor like lesions. Fibrous dysplasia, a tumor like lesion; tops the list with 20 (31%) cases [Figure 2].
The metastatic lesion to calvarium represents a surrogate marker of disease in the advanced stage., Fuchs and Prichard advocated trivial head trauma as a cause for development of calvarial osteosarcoma., Bone metastases from follicular thyroid cancer is around 7 to 28% as opposed to 1.4 to 7% in papillary carcinoma thyroid [Figure 3]. Nair et al. reported a holistic management of pediatric Calvarial Ewing's Sarcoma (CEWS) involving a multidisciplinary intervention. Paucity of literature are available regarding secondary deposits in skull from osteosarcoma as a primary pathology.,, The calvarial tumors may present as dural sinus invasion, compression of cranial nerves and cerebral cortex., In our study, remote history of trivial head trauma was diagnosed to have calvarial hemangioma [Figure 4] and intradiploic meningioma at presentation [Figure 5].
Computed tomography (CT) and Magnetic resonance imaging (MRI) provides a cross sectional imaging of the calvarial lesions. CT is highly useful for detecting the mineralized portion of the lesion and is highly specific in case of lesions such as hemangioma, Paget disease and fibrous dysplasia. The multiplanar reformatted images obtained with MDCT illuminates the detailed anatomical structure of such tumor as well as it acts as a guide to biopsy them. MRI scan because of its high contrast resolution is gold standard in identifying the nature and detailed architecture in diploic bone marrow along with their intracranial and extracranial extension. Fat saturated T1- weighted MR images reveals the best enhancement pattern as compared to CT or other sequences of MRI. Studies have suggested that in case of multiple calvarial lesions with avid radionuclide uptake bone scan is the preferred diagnostic tool. Those lesions whose preliminary work up suggests a possibility of dural venous invasion or high vascularity, are subjected to MR venography or cerebral angiography., Tumors with high vascularity and those causing dural venous invasion were embolized using IADSA before tumor excision.
A core needle or an open biopsy can be performed under local anesthesia or scalp block. Tomasian A. performed a retrospective study between 2014 and 2018 with a positive diagnostic yield of 86% using percutaneous CT- guided biopsy. This preoperative biopsy besides determining the histological character of lesion plays a vital role in management by confirming a metastatic focus and differentiating a new primary tumor versus synchronous primary tumor., In the present study, benign and tumor like lesions were the most common pathology and they underwent excision solely on radiological diagnosis. Those patients with metastatic calvarial lesions, the histopathology of the primary site represents the histology of metastatic deposits. Preoperative biopsy was advocated to patients in their advanced age without underlying malignancy with equivocal radiological evaluation. This helped us to subject them for neo-adjuvant therapy if indicated. This number in our study was minimal (four).
Application of autologous blood transfusion
In calvarial tumors with high vascularity, acute normovolemic hemodilution (ANH) was practiced at our center as a modality of perioperative autologous blood transfusion (ABT). ANH came into clinical practice in 1946, where a definite amount of blood is rapidly withdrawn from the patient and is replaced with equivalent volume of crystalloid or colloid liquids., In Preoperative autologous blood donation (PABD), patient's own blood is collected and preserved for several days prior to surgery, and reinfused back during surgical intervention. In the present study, a patient with large calvarial hemangioma and another patient with highly vascular intradiploic meningioma underwent acute normovolemic hemodilution.
Tessier recommended the application of split calvarial bone graft for reconstruction which become popular in surgical community by the end of 1932. The use of autologous bone graft has been considered as one of the best materials for reconstruction. Split calvarial graft should be avoided in elderly patients due to inadequate diploe width which makes it very difficult to harvest. In the present study, reconstruction of the calvarial defect during primary surgery using MRI compatible prosthetic material was found to be most acceptable with minimum complications.
The recent development of 3D reconstructs been a boon for craniofacial reconstruction surgery. This modality is based on 'Additive Manufacturing Technology' and employs 3D- Computer- aided design and manufacturing (CAD/CAM) software. The 3D reconstructs are indicated for:
These 3D construct have following advantages over the conventional grafts:
We believe that we should attempt this 3D customized construct in future cases of benign calvarial tumors like hemangioma, fibrous dysplasia and WHO grade 1 meningioma.
However, in malignant lesion; the life expectancy and extent of calvarial margin removal are two crucial limitations to this 3D reconstructs.
We used 3D reconstruct in a single case of fibrous dysplasia, which was involving the lateral wall of orbit and frontal sinus. This surgical adjunct offered an encouraging cosmetic result with patient safety.
In the present study, two cases; one of Dermato fibrosarcoma protuberance (DFSP) of scalp and another case of Myofibromatosis full thickness scalp excision was performed due to gross tumor infiltration. The plastic surgeon worked with our team to reconstruct the scalp defect by rotating the scalp flap along with the senior author (AKS).
Myofibromatosis was included in our study and DFSP was excluded as it was operated twice before undergoing definite management at our center.
Constans and Donzelli analyzed clinico radiological manifestations of 14 patients over two decades and suggested a specific therapeutic challenge associated with calvarial lesions. We encountered a case of metastatic follicular carcinoma thyroid who presented a unique challenge in the preoperative period. Metastatic thyroid tissue express sodium iodide symporter protein in their cells as an integral plasma membrane glycoprotein that mediates active transport of iodide into thyroid follicular cells. This makes radioactive iodine (RAI) a theragnostic agent of choice for diagnostic workup and treatment of metastatic thyroid carcinoma after total thyroidectomy. Iodine -131 is radioactive isotope of stable iodine with half-life of 8 days which emits beta particle & Gamma rays. Emitted gamma rays and beta particles are used for diagnostic and therapeutic purpose respectively. Frequently used dosage of I-131 for therapeutic purpose range from 150 to 300 mci, which can be repeated every 6 to 12 months as long as disease is iodine avid and responding to treatment.,
Fibrous dysplasia, Atypical and Anaplastic meningioma, were found to recur in our series.
Lesions with invasion of dural venous sinus, pathology involving paranasal sinus with extension to skull base and temporal bone lesion with mastoid air cells involvement are known to recur. These lesions recur due to incomplete excision, because of additional risks associated with sinus exploration and their extension in the paranasal sinus and few which were found to have non-excisable skull base extension.,
Management of recurrent lesions
New onset paresthesia, headache and repeated episodes of sinusitis are the presentation in case of aggressive extension of fibrous dysplasia to facial bone and paranasal sinus.,
Monostotic fibrous dysplasia (MFD) was the single most common pathology (n = 20) in our study and no Polyostotic fibrous dysplasia or McCune Albright syndrome was noticed amongst the study population. Incomplete extirpation of the lesion results in recurrence up to 25% of cases, especially with sinus or temporal bone involvement. No malignant transformation was noticed in this series so far, although literature suggests 1% risk of malignant transformation from fibrous dysplasia.
Study conducted by Ostrom et al. suggested 50% recurrence rate in grade II and 90% recurrence in grade III meningioma at five years of follow up. In our study, the locoregional spread of cancer cells along the traversing blood vessels was responsible for recurrence of anaplastic meningioma after complete excision.
Being a retrospective study, the long-term follow up was not so robust. Patients with total excision and indolent nature of lesions were found to have weaker compliance because of less aggressive pathology. Prospective study with long term follow- up should be planned to detect the exact behavior of residual disease.
We consider it noteworthy that there was significant difference in the preoperative deficits among young patients (age <50) as compared to those which were detected in older populations (age ≥50). The blood loss during excision of calvarial lesions was significantly high in malignant tumors as compared to those with benign tumors and tumor like lesions. Symptomatic patients with tumor invading eloquent areas of brain, despite having less severe radiology, may represent a subset of patients with incomplete recovery despite uneventful excision of tumor. During follow-up visit, there was significant improvement in KPS score. This favors the possibility that despite being asymptomatic, patients with calvarial lesion on radiology may have subclinical alterations in physiology and cerebral metabolism. This makes a robust criterion for surgical excision once scalp swelling is diagnosed on radiology, even if the individual is asymptomatic and without deficit.
Being a tertiary care hospital, the majority of the cases were complex and referred in their advanced stage. In our study, a very small number of patients were qualifying for the preoperative biopsy; thus, its importance could not be discussed. The heterogeneity of calvarial lesions, with diverse clinical and radiological presentations precludes correlation among the patients with isolated pathology. Prospective study with long term follow- up should be planned to detect the long-term outcome of Calvarial lesions. Multicentric study with larger number of patients will explain the progression free survival and exact behavior of residual disease.
The holistic management of calvarial tumors involve an integrated effort from medical oncology, anesthesiology, radiology and dedicated neuro-oncology team. The calvaria is a Pandora box with predominant benign pathologies. Following excision of calvarial lesions, there was significant improvement in the KPS score. Symptomatic patients with underlying malignant pathology reflect a guarded outcome as compared to asymptomatic counterparts.
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The authors certify that they have obtained all appropriate patient consent forms. In the form, the patient(s) has/have given his/her/their consent for his/her/their images and other clinical information to be reported in the journal. The patients understand that their names and initials will not be published and due efforts will be made to conceal their identity, but anonymity cannot be guaranteed.
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Conflicts of interest
There are no conflicts of interest.
[Figure 1], [Figure 2], [Figure 3], [Figure 4], [Figure 5]
[Table 1], [Table 2], [Table 3], [Table 4]