PMC3588111_01
(A) Sagittal T1 weighted image demonstrates a 1.8 cm T1 isointense round mass in the lateral subcutaneous soft tissues, plantar to the peroneal tendons. (B) The lesion is hyperintense on T2 fat suppressed images. (C) The lesion demonstrates a small area of central contrast enhancement on T1 fat suppressed images (whereas it demonstrated homogenous enhancement on earlier studies). A smaller lesion is partially seen posterior to the dominant lesion.
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F1
Computed tomography (CT)/Magnetic resonance imaging (MRI) revealed multiple soft tissue masses throughout the left mid and hindfoot, with the largest mass located in the lateral hindfoot and measuring 1.8 cm in greatest dimension, having grown from 1.37 cm 8 months prior and correlating to the location of his current symptoms (Figure 1).
Representative section from the left foot mass shows vascular tumor containing perivascular proliferation of small cuboidal epithelioid cells without atypia around open vascular spaces (HandE stains, A, 40x; B, 200x).
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F2
Histologic evaluation from the most recent surgical excision (6 years prior to presentation to our service) consisted of multiple samples, all consistent with glomangiomatosis (Figure 2).
(A) Lateral view of immobilization device. Small strips of tape hold gold fiducials over placeholder tattoo markings. (B) Medial view of immobilization device with two placeholder tattoos. (C) Lateral view of immobilization device with three placeholder tattoos.
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F3
Due to the difficulty of implanting fiducials in the foot, five golden fiducials were affixed to the patient's foot at the time of CT simulation and tattoos were used to mark their positions (Figure 3).
The CyberKnife treatment plan utilizing-fused CT and MRI scans of the left foot. The gross tumor volume was outlined on both scans and prescribed a dose of 3000 cGy. Thin orange is the CT-GTV, which was treated to a minimum of 3122 cGy and a maximum of 4139 cGy. Thin red represents the MRI-GTV, which was treated to a minimum of 3289 cGy and a maximum of 4225 cGy. Each GTV received 100% of the prescribed dose. The two GTVs were fused with an extension of 2 mm to create the CTV (thick orange) and a margin of 5 mm was added (thick purple) was added to create the PTV. The talus was outlined and kept to a maximum of 2260 cGy.
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F4
The CTV was expanded by 2 mm to create the planning tumor volume (PTV) (Figure 4).
(A) Sagittal T1 weighted image obtained 6 months following the patient's SBRT treatment demonstrates interval decrease in the size of the dominant mass to 1.1 cm. (B) It remains hyperintense on T2FS images. (C) It also demonstrates homogeneous enhancement on T1 fat suppressed post contrast images.
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F5
His MRI at 6 months post-treatment showed no new lesions as well as a decrease in size of the target lesion to 1.1 cm in maximal dimension, a reduction of 0.7 cm (Figure 5).
(A) Sagittal T1 weighted image obtained ~2 years following the patient's SBRT treatment demonstrates interval development of an enlarging T1 isointense nodule within the subcutaneous soft tissues dorsal to the fourth-metatarsal diaphysis. (B) It is hyperintense on T2 fat suppressed images. (C) Similar to previously identified masses, it demonstrates contrast enhancement on T1 fat suppressed post contrast imaging.
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F6
This is consistent with the most recent imaging, which showed an increase in size to 0.9 cm of an existing nodule seen on previous studies (Figure 6).