CYSTIC 'MIRROR' BRAIN METASTASIS

 

 

Deepak Agrawal, AK Mahapatra

Departments of Neurosurgery, All India Institute of Medical Sciences, New Delhi-110029

 

 

ABSTRACT

 

We describe a case of a 50-year-old male, nonsmoker, who presented with one-month history of memory distubances and behavioural changes. CECT head showed bilateral frontal 'mirror' cystic lesions with mild peripheral enhancement. The patient was subjected to left frontal craniotomy, cyst aspiration and biopsy of the cyst wall. As histopathalogical examinanition revealed it to be a poorly differentiated carcinoma of unknown origin, he was subsequently referred for radiotherapy and chemotherapy. In difference to the recent enthusiasm for radical excision of such lesions, we are of the opinion that a conservative approach involving decompression of the cyst with biopsy of the cyst wall is more suitable in such patients, as chances of neurological deterioration following radical surgery are high, especially if the lesion is in proximity to the eloquent areas.

 

KEY WORDS: cystic brain metastasis, mirror lesions

 


 

Fig 1: Contrast enhanced CT head, axial image showing bifrontal cystic lesions with irregular ring enhancement.

 

 


INTRODUCTION

Cystic brain metastasis may prove to be a daignostic and therapeutic challenge to the treating neurosurgeon. We report a case of cystic brain metastasis with unknown primary managed by decompression of the cyst along with biopsy of the cyst wall.

 

CASE REPORT

A 45-year-old male presented with one month history of progressive dysphasia and alteration in behavior. He had right hemiperesis of recent onset and was in altered sensorium one day prior to presentation. There were no comorbid medical problems and no history of any addictions could be elicited. On examination patient was drowsy and dysphasic, with right hemipersis of grade 4/5. A contrast enhanced CT head revealed bilateral frontal 'mirror' cystic lesions with mild peripheral enhancement (fig 1). In view of the deteriorating clinical condition, he was taken up for emergency surgery and a left frontal craniotomy with initial cyst aspiration followed by biopsy of the cyst wall was performed. The opposite side cystic lesion was not touched. Postoperatively, the patient’s sensorium improved and the hemiperesis also resolved. As histopathological examination of the cyst wall revealed a poorly differentiated carcinoma of unknown origin, he was subsequently referred for radiotherapy and chemotherapy.

 

DISCUSSION

 

Cystic metastases in the brain are relatively rare and only few case reports are available in literature.1-6The cystic changes may occur due to necrosis in a solid lesion as a result of the tumor outgrowing its blood supply or less commonly due to cyst formation by the tumor itself. Certain tumors such as ductal carcinoma of the breast and adenocarcinoma of the lung are more frequently associated with metastatic cyst formation, by virtue of their being the most common primary tumors. 7 These cases can be difficult to diagnose, as radiologically, in absence of a known primary, the lesion could be confused with brain abscess or a cystic astrocytoma. MR Spectroscopy may provide some clue as to the pathology of the lesion, but by no means can be taken as an infallible diagnostic aid. Though diffusion-wieighted MRI has reported to be useful in differentiating between abscesses and cystic or necrotic tumors, 8 recent reports have shown that findings on diffusion-wieighted MRI during the early capsule formation stage in abscesses and early tumor necrosis are probably similar and must be interpreted with caution.9 Stereotactic biopsy may also not be conclusive as a necrotic tissue and abscess may both contain polymorphs. The differentiation is important as in cases of multiple cystic metastases, directly subjecting the patient to radiotherapy and/or chemotherapy may avoid the morbidity associated with a major surgical procedure. This becomes even more relevant in view of the recent findings that cystic metastasis have a worse prognosis as compared to their solid counterparts. 10 In our patient the progressive hemiparesis and altered sensorium made the decision to operate easier.

Treatment protocols have ranged from conservative management with radiotherapy and chemotherapy, to cyst aspiration and radical excision of its wall. 9 We believe that a middle path involving decompression of the cyst with biopsy of the cyst wall is more suitable in such patients as chances of neurological deterioration following radical surgery are high, especially if the lesion is in proximity to the eloquent areas.

 


REFERENCES

 

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