Misdiagnosis of malignant meningioma in subcutaneous soft tissue of the forehead:A case report

Mengjuan Li,Min Qi

Department of Plastic Surgery,Xiangya Hospital,Central South University,Changsha 410008,Hunan,China

Keywords:Malignant meningioma Anaplastic meningioma Meningioma metastasis

ABSTRACT Meningiomas,the most common intracranial primary tumors,are always benign.Extracranial and distant metastases can occur in malignant meningiomas.This case report describes a male in his 50s with malignant meningioma and metastases to the subcutaneous soft tissue.Preoperative color Doppler ultrasound showed that the tumor had an abundant blood flow.Intraoperative pathological examination revealed a malignant tumor.Postoperative pathological examination revealed malignant tumors in the forehead;thus,malignant meningiomas were suspected.Immunohistochemistry revealed grade III malignant meningioma.Malignant meningiomas have the ability to readily spread and metastasize;however,cases of malignant meningiomas disintegrating the bone and metastasizing to the subcutaneous part of the head have not been reported.

1.Introduction

Meningioma is the most common intracranial primary tumor and is mostly benign.The incidence of malignant meningiomas is relatively low.Malignant meningiomas can have extracranial and distant metastases,but subcutaneous soft tissue metastases to the trunk and limbs are rare.1This report introduces a case of asymptomatic malignant meningioma with subcutaneous soft tissue metastasis to the forehead.

2.Case presentation

A male in his 50s developed a subcutaneous tumor on his forehead for more than one year.The skin on the tumor surface was normal,and there were no other clinical signs(Fig.1).The patient was admitted to another hospital,and regular follow-ups were suggested.Three months ago,the patient showed obvious enlargement of the tumor and accordingly visited the Department of Plastic and Aesthetic Surgery at Xiangya Hospital of Central South University on October 21,2021.Color Doppler ultrasound indicated a 42 mm × 41 mm hypoechoic nodule with abundant blood flow in the subcutaneous soft tissue of the forehead.The nodule was lobulated,close to the bone surface,and irregular in shape.The patient was then admitted to the ward for immediate surgical intervention.Routine examinations were performed before surgery,and no obvious abnormalities were found.Therefore,the tumor was excised and intraoperative biopsy was performed the following day.During the operation,a single,round,and firm subcutaneous mass was observed close to the periosteum,and the bleeding continued.Upon peeling off the tumor,it was observed to have a fish-like morphology.Results of the pathological examination of the intraoperative forehead mass sample revealed a malignant tumor.After obtaining the required approvals from the patient’s family during the operation,we thoroughly removed the peripheral frontalis muscle and periosteum and closed the wound.The patient was discharged,and a pathological examination was performed for the excised tumor.The patient was discharged 2 days post admittance.Postoperative pathological diagnosis indicated a malignant frontal tumor,which was identified as malignant meningioma.Immunohistochemical diagnosis indicated a malignant meningioma (World Health Organization (WHO) grade III) with Ki67 (hot spot 10%+),EMA (+),PR (+),and SMA (-) (Fig.2).The head magnetic resonance imaging (MRI) examination was performed in a local hospital,which showed a spindle-shaped abnormal signal shadow under the bilateral frontal medial plate,with bilateral frontal lobe compression and frontal skull invasion.Subsequently,we were informed that the patient had been treated in the Neurosurgery Department of People’s Hospital Affiliated to Peking University Medical College.

Fig.1.Preoperative photos of the patient’s head.A single round and subcutaneous tumor with normal skin on the surface.

Fig.2.Pathological diagnosis:Frontal malignant meningioma,WHO grade III.In both sections,tumor cells and many pathological mitotic phases can be seen simultaneously.(A) The black circle shows a large patch of tumor cells.(B) The arrows indicate pathological mitotic phases.

3.Discussion

Meningioma,which originates from arachnoid cap cells,is the most common primary intracranial tumor and is characterized by having a complex histology.2According to the WHO,meningiomas are classified into three grades.Grade III is the anaplastic (malignant) meningioma.The incidence of atypical and malignant meningiomas is less than 10%,3,4while the incidence of WHO grade III malignant meningioma is only 1.7% among all meningioma cases.5Both benign and malignant meningiomas have the ability to metastasize,with an overall probability of approximately 0.1%.Meningiomas can metastasize to distant organs such as the lungs,bone,spinal cord,and liver;the rates of extracranial and distant metastases of anaplastic meningioma are approximately 30%,6,7while its recurrence rate is approximately 70%.Subcutaneous soft tissue metastasis has been rarely reported.1,7–10Clinical manifestations of meningioma depend on the primary focal site and commonly include headache,localized symptoms,and epilepsy.The disease can progress without obvious clinical signs.11Malignant meningiomas often have characteristic computerized tomography and MRI manifestations,but the diagnosis mainly depends on the pathological examination and immunohistochemistry.Therefore,treatment of malignant meningiomas should be systematic.The Simpson grading scale of meningioma resection has provided a detailed management strategy for meningioma.11Surgical resection combined with radiotherapy are performed to completely excise the tumor and prevent recurrence.

The reported case was of an extracranial malignant meningioma,and this asymptomatic extracranial malignant meningioma had an undetected onset.Its clinical manifestations are similar to those of subcutaneous tumors;thus,it is often misdiagnosed clinically.Its diagnosis should be differentiated from that of sebaceous cysts,lipomas,and other intracranial tumors.Clinical diagnosis should be based on physical examination in combination with pathological examination and immunohistochemical results.This patient was in his 50s,and this age is a risk factor for malignant meningioma as the incidence of this condition increases with age.Preoperative physical examination of the patient showed that the subcutaneous mass was firm and hard to move upon touch.Color Doppler ultrasound examination showed that the mass had an abundant blood flow,and hemorrhage occurred when the mass was cut during the operation.The unclear mass boundary was closely adhering to the periosteum.The fish-like morphology of the excised mass indicated malignancy.Physical examination in combination with postoperative pathology and immunohistochemistry indicated the presence of malignant meningioma.

4.Conclusion

The onset of malignant meningioma is always undetected;thus,an accurate diagnosis can be made by a combination of clinical experience,imaging examinations,pathological examinations,and immunohistochemistry.Surgical resection is the best strategy for the management of malignant meningiomas.During surgery,the tumor and surrounding tissues should be removed till clean margins are achieved.As malignant meningiomas are aggressive and have high recurrence rates,head MRI and color Doppler ultrasound of the forehead should be regularly performed during the follow-up period.In conclusion,surgical resection,in combination with postoperative radiotherapy and targeted therapy,can lead to complete eradication of the tumor and prevent its recurrence.

Ethics approval and consent to participate

The need for ethical approval and consent to participate was waived due to the retrospective nature of this study.

Consent for publication

The patient gave written informed consent to publish the data contained within this study.

Competing interests

The authors declare that they have no competing interests.

Authors’contributions

Li M:Data curation,Resources,Writing-Original draft.Qi M:Supervision,Writing-Review and Editing.