Abnormal brain image: is it a brain tumor or necrosis caused by treatment?

Primary brain tumors are not uncommon.
In addition, the brain is also a common metastasis site for cancer cells.

However, the brain image is abnormal, sometimes not necessarily a tumor, or it may be brain necrosis caused by treatments such as radiotherapy.

The imaging features of the two are similar and it is difficult to distinguish.

If the two are confused, treatment will be delayed, causing unnecessary burden and pain to the patient.

Indistinguishable brain tumors and radiation necrosis Stereotactic radiosurgery (SRS) is a type of radiotherapy.
It is a traditional treatment method for single or a small number of multiple brain metastases.
For example, the familiar gamma knife belongs to one of them.

Clinical SRS is generally used for patients with better physical conditions.

SRS treatment has more concentrated radiation points, less damage to normal tissues, less side effects, and can control tumor development in a short period of time, but its shortcomings are also obvious.
It can cause vascular damage and local inflammation, and the resulting radiation brain necrosis can be caused to patients.
Bring great pain.

What's more troublesome is that radiation-induced brain necrosis and brain tumors are sometimes difficult to distinguish in imaging, and the symptoms are not much different.
This poses a great challenge to clinicians who evaluate the efficacy through head imaging.

Brain tumors often lack blood vessels and may have obvious necrotic areas in the center.
This imaging feature can easily be confused with radiation necrosis.

Is it necrosis caused by radiation, recurrence of metastases, or other tumors? It's like looking at flowers in the fog, completely unable to judge.

Mistaking Brain Tumors for Radiation Necrosis The case we are going to introduce to you today fully reflects the complexity of medicine and the difficulty of treatment.

Ms.
A, 60, has a relatively long smoking age and smokes about 30 packs a year on average.

The first visit in October 2018 was due to headache, dyskinesia of the right upper limb and trunk ataxia that lasted for 3 weeks.

According to Ms.
A's medical history and clinical manifestations, the doctor performed imaging examinations of her head and chest and found suspicious lesions in the right cerebellum, the right parietal lobe of the brain, and the right upper lobe of the lung.

Through a biopsy of the paratracheal lymph nodes, Ms.
A was diagnosed with lung adenocarcinoma with KRAS G12C mutation and high PD-L1 expression (>50%).

Subsequently, the doctor and Ms.
A determined the treatment strategy: SRS radiotherapy for two isolated brain metastases; systemic treatment included a phase 2 of niraparib combined with pembrolizumab (Pembrolizumab, K drug) Clinical Trials.

From December 2018 to June 2019, Ms.
A developed new brain lesions, which included another lesion in the right temporal lobe located in the middle of the previous lesion.

For this reason, she had to receive SRS radiotherapy again (Figure 1).

Figure 1 Ms.
A's MRI follow-up during the treatment process (yellow star indicates that SRS was performed at the corresponding time point) due to the appearance of new lesions and was evaluated as "disease progression".
Ms.
A withdrew from the phase 2 clinical trial.

The doctor formulated a second-line treatment plan for her, namely K drug combined with chemotherapy.

Two months later, Ms.
A’s headache symptoms gradually worsened.

Because of receiving SRS, immunization and targeted therapy, doctors first considered that the worsening headache was caused by "radiation necrosis", but after receiving glucocorticoid treatment, these "necrosis foci" did not seem to get any better.

MRI showed that Ms.
A's right temporal lobe and the surrounding cerebellum were enlarged (Figure 2A).

In contrast, lung masses and lymph node lesions gradually shrank during follow-up in 2019.

Subsequently, Ms.
A received pemetrexed combined with bevacizumab treatment, and at the same time escalated intervention for possible "radiation necrosis".

Unfortunately, the escalation intervention did not have a significant effect on Ms.
A's "radiation necrosis".

From January to May 2020, Ms.
A developed new neurological symptoms, including right hand tremor, blurred vision, dysarthria and personality changes.

Subsequently, her right cerebellar lesions and right tremor gradually improved, but the right temporal lobe lesions continued to expand under the treatment of bevacizumab and glucocorticoids (Figure 2B).

Figure 2 Ms.
A's head MRI (A) Representative MRI spectra of metabolites in the right temporal lobe (upper) and right cerebellum (lower) in December 2019; (B) Right temporal lobe (upper, white) in April 2020 Contrast magnetic resonance perfusion imaging of dynamic susceptibility of the right cerebellum (lower perfusion, white diamonds) and high perfusion shown by the arrow.

The condition worsened and Ms.
A had to be hospitalized again and underwent a decompression resection of the right temporal lobe brain mass to relieve her psychiatric symptoms.

As a routine clinical diagnosis and treatment, the doctor performed a pathological examination of the tumor, and something unexpected happened: pathology showed that Ms.
A’s temporal lobe brain tumor was a glioma (IDH wild type, MGMT promoter methyl), not lung cancer metastasis (Figure 3).

Figure 3 The histopathological evaluation of Ms.
A's right temporal lobe tumor after excision showed glioma (A) HE staining; (B) GFAP staining; (C) Masson staining; (D) HE staining specimens showing perivascular tumors Cell necrosis.

After the operation, Ms.
A's neuropsychiatric symptoms gradually improved, her headache eased, but dysarthria still existed.

After the doctor assessed her physical condition, she considered it suitable for hypofractionated adjuvant radiotherapy and chemotherapy.

She accepted the CT simulated radiotherapy plan, but after finally weighing the risks and benefits, she did not stay in the hospital to continue treatment.

The importance of accurate identification of abnormal brain imaging.
Ms.
A's primary lung and lymph node lesions have improved significantly after receiving treatment, which is in sharp contrast with the obvious enlargement of new lesions in the temporal lobe.
At this time, it should be suspected that the new brain lesions are not metastases , But the possibility of other diseases.

If the identification is difficult, and the symptoms that appear meet the indications for surgical biopsy, options such as surgery should be considered.

Patients receiving immunotherapy, targeted therapy, and cranial SRS radiotherapy are more likely to develop brain necrosis.

However, radionecrosis and brain tumors are sometimes difficult to distinguish in imaging, and the symptoms are not much different, but the treatment methods are completely different.

Therefore, be extra cautious when identifying.

Tumor patients have limited time, and unsuitable treatment methods not only increase the burden on patients and their families economically, but also waste their precious time.

Pay attention to the cancer degree, download the cancer degree APP, and learn about the latest anti-cancer and anti-cancer knowledge.

References Qian D et al.
Co-Occurrence Conundrum: Brain Metastases from Lung Adenocarcinoma, Radiation Necrosis, and Gliosarcoma.
Case Rep Oncol.
2021; 14: 487-492.