PMC9699841_01
Adenoid cystic carcinoma (ACC) in a 50-year-old man (Case 1). Gadolinium-enhanced, T1-weighted magnetic resonance, imaging revealed an enhanced tumor extending from the nasal cavity to the suprasellar region (a). The tumor was pathologically confirmed as ACC, exhibiting cribriform growth with myoepithelial differentiation (b). After two resections, he experienced recurrence in the superior orbital fissure, at age 56, and stereotactic radiosurgery (SRS) was performed with a marginal dose of 20 Gy to a 50% isodose line (yellow line) in axial (c), coronal (d), and sagittal plane (e) Green lines indicated marginal dose line of 10 Gy, 18 Gy, and 24 Gy. A remote metastasis was detected in the parapharyngeal space, with marginal recurrence after its resection. We performed the second SRS for the parapharyngeal metastasis with the same parameters and the planning was shown in axial (f), coronal (g), and sagittal plane (h) with the previous planning in blue line. Yellow line indicated 20 Gy to a 50% isodose line, and green lines indicated marginal dose line of 10 Gy, 12 Gy, and 18 Gy. Both lesions were in remission at the last follow-up: 36 months after the first SRS for recurrence in the superior orbital fissure and 9 months after the second SRS for recurrence in the parapharyngeal space (i-k).
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F1
Magnetic resonance imaging (MRI) revealed a heterogeneously enhanced tumor extending from the nasal cavity to the suprasellar region [Figure 1a]. The tumor was pathologically confirmed as ACC through transnasal biopsy [Figure 1b], and an endoscopic endonasal approach was used for gross total resection. Four years later, local recurrence was observed in the right superior orbital fissure [Figure 1c]. SRS with a prescription dose of 20 Gy to a 50% isodose line using the Gamma Knife ICON with Leksell frame head-fixation (Elekta AB, Stockholm, Sweden; [Figures 1c-e]). Since the patient was blind in the right eye after surgery for a pituitary adenoma at age 20, we were not concerned about radiation injury to the optic nerve; the mean and maximal radiation exposures to the optic chiasm were 2.0 and 3.3 Gy, respectively. Although the metastasis was resected through an endoscopic endonasal approach, marginal tumor recurrence was observed in the parapharyngeal space [Figure 1f]. We performed a second SRS with the same marginal dose, isodose line, and procedure as for the first SRS [Figures 1f-h]. At 36 months after the first SRS and 9 months after the second SRS, complete local remission was maintained for both tumors, and no radiation necrosis was observed [Figures 1i-k].
PMC9699841_02
A 56-year-old woman underwent resection for a tumor growing next to the right orbit and the anterior skull base (Case 2). The tumor was pathologically diagnosed as adenoid cystic carcinoma arising from the lacrimal gland (a). Despite repeated resection, she experienced recurrence around the right cavernous sinus and orbit. We performed stereotactic radiosurgery for the anterior skull base metastasis, with a marginal dose of 20 Gy to a 50% isodose line (yellow line) in axial (b), coronal (c), and sagittal plane (d) Green lines indicated marginal dose line of 10 Gy, 18 Gy, and 24 Gy. The tumor shrank considerably in the next 5 months (e).
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F2
It was resected and pathologically confirmed as ACC arising from the lacrimal gland [Figure 2a]. The tumors in the right cavernous sinus were resected repeatedly along with subsequent systemic chemotherapy (using docetaxel), but further recurrence was confirmed in the right anterior skull base [Figure 2b]. SRS for maximum control of the skull base lesions since they were already irradiated. SRS with a prescription dose of 20 Gy to a 50% isodose line was performed using the Gamma Knife 4C (Elekta) with frame head fixation [Figures 2b-d].