Familial glioblastoma clustering in adult patients: a case report of two non-twin siblings and review of the literature

Introduction

Glioblastoma multiforme (gbm) is the most malignant tumor of the central nervous system with an extremely poor prognosis.¹ The average overall survival is 12–15 months after first diagnosis. Two molecular subtypes of gbm are described, divided into primary and secondary gbm. Primary gbm is characterized by de novo development and usually occurs in elderly patients over 50 years of age. Molecular analysis reveals an overexpression of EGFR, loss of heterozygosity of chromosome 10q and phosphatase and tensin homolog mutations. Secondary GBM occurs mainly in younger patients and its genetic profile is characterized by tumor protein p53 (TP53) mutations and isocitrate dehydrogenase 1 (IDH-1) mutations.²

There is faint evidence for the involvement of environmental factors in the genesis of glioblastoma, such as nonionizing electromagnetic fields and ionizing radiations.³ Furthermore, several hereditary tumor syndromes are associated with an increased occurrence of gbm in childhood and adolescence, for example, neurofibromatosis type-1, familial melanoma-astrocytoma syndrome, Li-Fraumeni syndrome, and Turcot syndrome.^4–7

Familial gbm in the adult is extremely rare. A review of the literature revealed many well-documented descriptions of familial gbm in children, but there were only three case reports dealing with familial gbm in adult patients.^8–10

This report describes familial gbm in two adult siblings. Interestingly, both patients suffered from multifocal gbm and were diagnosed at the same age of 63 years.

Case description

Case 1

Sibling 1 was the older sister, a 63-year-old female without malignant disease in her history (Table 1). She suffered from sudden paresthesia, ataxia, and vertigo. Brain magnetic resonance imaging (mri) disclosed mass lesions with gadolinium enhancement in the left parieto-temporal and the left frontal lobe infiltrating the splenium to the contralateral hemisphere with a total volume of 54.52 cm³ (Figure 1A-C). Craniotomy and partial resection of the tumor were performed 1 week after the first occurrence of clinical symptoms. Histopathologic examination of the tissue revealed a primary gbm, IDH-1 wild type (Table 2). The patient postoperatively developed focal epilepsia in the left upper limb, which was successfully treated with levetiracetam. She was discharged 14 days after surgery.

Table 1 Clinical data and oncologic history of both cases

Figure 1 Magnetic resonance imaging (mri) scan of the neurocranium, gadolinium-enhanced T1-weighted sequences. (A-C) Sibling 1. mri axial (A), coronal (B) and sagittal view (C) large mass located in the parieto-temporal lobe, multifocal localization, extension into the corpus callosum and infiltration to the right hemisphere. (D-F) Sibling 2. mri axial (D), coronal (E) and sagittal view (F). Tumor mass located in the parieto-temporal lobe with periventricular, ependymal spread. Multifocal localization, up to the right frontal and temporal regions.

Table 2 Neuropathologic results of tumor samples

Concomitant radiation with temozolomide (tmz) was performed, followed by chemotherapy with tmz alone. The first recurrence occurred in the dorsal corpus callosum, left occipital lobe and left temporal lobe 1 year after the first diagnosis of gbm. A second palliative radiation of the recurrence was undertaken. The patient died 63 weeks after the first diagnosis of multifocal gbm.

Case 2

Sibling 2 was the younger brother of the patient described as case 1, a 63-year-old male without malignant diseases (Table 1). He presented to our institution with a 1-year history of progressive gait disturbance and motor aphasia. The mri scan revealed multifocal lesions in the left parieto-temporal and frontal lobe combined with ependymal spread and a total tumor volume of 8.97 cm³ (Figure 1D-F). Craniotomy and partial resection of the tumor in the left parietal lobe were performed. Histopathology disclosed primary gbm, IDH-1 wild type (Table 2). The patient was discharged 5 days after surgery with motor dysphasia, but the absence of further neurologic sequelae. Combined radiation and chemotherapy had been advised, but, in view of his sister’s fate, the patient refused any further therapy or clinical follow-up examinations and died 3 months after the first diagnosis of gbm.

Discussion

In this study, we describe a sister and her younger brother who both suffered from gbm at an identical age with nearly the same tumor localization and multifocal appearance. Furthermore, the histological, immunohistochemical, and molecular findings can be considered to be nearly identical.

Familial gbm has been associated in pediatric patients with specific tumor syndromes (Table 3).

Table 3 Pediatric tumor syndromes with reported familial clustering of glioblastoma multiforme

In contrast to this, the familial occurrence of gbm in adult patients is an extremely rare event, with only a few case reports found in the recent literature (Table 4).

Table 4 Reports on familial gbm in the adult

Heuch et al described two brothers aged 65 and 68, one case only diagnosed at autopsy.⁹ The second report of adult familiar gbm was illustrated by Hardman: one pair of identical twins suffered from gbm, the first at the age of 61 and the second at 63. Normal karyotypes of blood leukocytes and similar environmental exposure are described.¹⁰ Thirdly, Ugonabo published a report of two brothers with the diagnosis of gbm at the age of 63 and 81 years.⁸ There was no clinical information given about any environmental risk factors or genetic alterations to depict pathophysiologic mechanisms.

In summary, all four case reports of adult familiar gbm describe elderly patients with an average age of 65.9 years at first diagnosis and seven of eight patients are male. Frequent tumor localizations are the temporal lobe (54%, 6 of 11 tumors), the parietal lobe (36%, 4 of 11), occipital lobe (27%, 3 of 11), and the frontal lobe (18%, 2 of 11). A multifocal localization was detected in half of the patients. The left hemisphere was more often implicated than the right hemisphere (63% left vs 36% right). The average overall survival was 6 months. These findings are in good accordance with the natural epidemiology of primary gbm, pointing to a statistical coincidence as an explanation for the familial occurrence, rather than to a causal connection.¹¹

Integrated diagnosis was only available in the two current cases due to the retrospective nature of case reports. In the present cases, the integrated diagnosis and the detailed immunohistochemical markers can be considered to be almost identical, revealing the diagnosis of primary gbm, IDH-1 wild type.

However, we detected discrete differences concerning MGMT promoter methylation and the number of immune cells within the tumor stained by cluster of differentiation 68. In case 1 MGMT promoter methylation was classified as absent, whereas in case 2 the MGMT promoter was strongly methylated. These findings would have suggested a better overall survival and chemotherapeutical response for case 2 compared to case 1, as has been detailed by the MGMT promoter methylation score,¹² but unfortunately patient 2 declined further therapy.

Differing results were also shown for the immunohistochemical staining of C12orf75, whereas the staining for ApoC1, leucine zipper protein 6 (LuzP6), and myotrophin were rather similar, all of them proteins that have been associated with cystic appearance of gbm (Figure 1, Table 2).¹³

The intriguing finding of tumor occurrence at nearly the same age with a large amount of corresponding radiological and neuropathological results inspires the search for a potential common pathogenetic mechanism. Further detailed genetic analysis would help to describe the precise driver genes to distinguish between familial hereditary occurrence and mere coincidence.

Ugonabo et al performed cytogenetic analysis in one sibling and illustrated multiple chromosomal abnormalities, such as triploidies 4, 8, 12 and 22, and loss of heterozygosity of 1 p, 9 p and 10.⁸ All of these chromosomal aberrations have already been well described in gbm.^14–19 However, the frequent hallmarks of gbm, gain at chromosome 7 and loss of chromosome 10, were absent, thus, the genetic imbalances illustrated did not allow to define a “familial clustering subtype”.

Conclusion

In addition to the two gbm siblings presented in this report, a review of the literature revealed only a very limited number of reports on familial gbm clustering in adults. Different from the pediatric population and although supplementary and improved genetic studies may disclose further common aberrations in the future, our results support the hypothesis of statistical coincidence without an underlying genetic cause.