Primary Intracranial Squamous Cell Carcinoma Arising from an Epidermoid Cyst: Successful Management with Subtotal Resection and Gamma Knife Radiosurgery in an Elderly Patient

Round 1

Reviewer 1 Report

Comments and Suggestions for Authors Given the unique nature of the case, it would be interesting to emphasize the importance of registries of rare tumors to facilitate research.

Author Response

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Author Response File: Author Response.docx

Reviewer 2 Report

Comments and Suggestions for Authors

Primary Intracranial Squamous Cell Carcinoma Arising from an Epidermoid Cyst: Successful Management with Subtotal Resection and Gamma Knife Radiosurgery in an Elderly Patient

General: This paper is a case study (rather than research paper) of a special/rare primary intracranial squamous cell carcinoma (SCC) adjacent to a epidermoid cyst in an elderly patient. Due to patient medical frailty total tumor resection was not indicated as the tumor was extending into the auditory canal and was in close proximity to the brainstem and vestibulocochlear nerve complex, the Gamma Knife stereotactic Gamma Knife treatment was clearly beneficial over conventional external beam radiation therapy (EBRT) subsequent to surgical resection using IMRT.

I thought the manuscript was well written. The description of the patient’s case was very thorough and understandable. The prescribed dose to the patient was reasonable, but more importantly, patient has done well past 18 months. It would be good to know if the patient continues to do well beyond the 18-month period if she is still being monitored by the authors.

From the perspective of a medical physicist, the collimators within the Gamma Knife unit are superior to the multi-leaf collimators in a linear accelerator with nonexistent transmission leakage and sharper penumbra at the edges of the radiation field. The smaller collimator sizes on the Gamma Knife and head localization apparatus ensures precise positioning of the radiation dose to the target volume. Furthermore, stereotactic radiation surgery offers radiobiological benefits over conventional IMRT techniques due to the abscopal effects, improved immune response due to the local release of tumor specific T cells, and may cause significant local vascular damage that results in greater cell killing over lower fractionation regimens. The authors might want to consider adding these points to strengthen their manuscript.

I don’t have any other constructive criticisms of this manuscript.

Author Response

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Reviewer 3 Report

Comments and Suggestions for Authors

This report describes a clinically interesting case of primary intracranial squamous cell carcinoma arising from malignant transformation of an intracranial epidermoid cyst. Following maximal safe subtotal resection, adjuvant Gamma Knife radiosurgery (GKS) was delivered to the residual lesion, with no evidence of progression for 18 months. However, the following points remain insufficiently addressed, and in its current form a revision is appropriate.

i) Clarify the basis for “primary” disease:
Please explicitly describe how metastatic SCC was excluded, including whether systemic work-up was performed (e.g., PET/CT, chest–abdominal CT, and otolaryngology evaluation) and summarize the results.

ii) Objective follow-up and wording:
Is “disease-free” accurate, or should this be described as “progression-free” / “no radiographic evidence of progression”? Please add representative serial MRI images (e.g., pre-GKS and 12 months post-GKS).

iii) Resolve inconsistencies in ethics statements:
Please harmonize the ethics and consent statements (i.e., whether consent was waived or written informed consent was obtained) and use wording appropriate for a case report.

Author Response

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Author Response File: Author Response.docx

Round 2

Reviewer 3 Report

Comments and Suggestions for Authors

Thank you for your careful revisions and detailed responses. Overall, you have addressed the main concerns appropriately—particularly by clarifying the systemic work-up supporting a “primary” diagnosis, replacing “disease-free” with more accurate wording (e.g., “progression-free” / “no radiographic evidence of progression”), and adding representative serial MRI images to objectively demonstrate radiographic stability/response.