PMC4896124_01
71-year-old man with ruptured epidermal cyst. Composite PET/CT image (sequence: CT. PET, fused PET/CT in coronal, sagittal and axial projections) shows a focus of increased F-18 FDG uptake at the posterior neck (SUV: 4.6). This positive PET finding corresponds to a slightly spiculated soft tissue lesion on transmission CT (arrows). The PET and CT features of this lesion are suspicious for recurrent malignant melanoma.
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In the posterior aspect of the neck, PET/CT (Figure 1) showed an abnormal focus of F-18 FDG accumulation (SUV: 4.6, arrows) corresponding to a spiculated soft tissue nodular lesion on transmission CT.
71-year-old man with ruptured epidermal cyst. Composite PET/CT image (same sequence as thee one of Figure 1) at a level inferior to the one depicted by Figure 1, shows well-defined soft tissue nodules of the posterior neck exhibiting no radiotracer accumulation (arrows).
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PET/CT also demonstrated additional well-marginated posterior neck nodules without radiotracer uptake (Figure 2) suggestive of benign lesions such as epidermal or sebaceous cysts.
71-year-old man with ruptured epidermal cyst. Photomicrograph shows the intact cyst (H and E, x10) with epidermal lining and surrounded dermis and subcutaneous tissue.
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All the three posterior neck nodules were excised and diagnosed as epidermal inclusion cysts by histology (Figure 3).
71-year-old man with ruptured epidermal cyst. Photomicrograph (H and E, x10) shows the ruptured epidermal cyst at the junction of reticular dermis and subcutaneous fat. There is dense inflammation surrounding the ruptured cyst secondary to release of keratin cyst contents into adjacent soft tissue.
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The one, which exhibited positive radiotracer accumulation, appeared to be a ruptured epidermal cyst with prominent surrounding granulomatous inflammation (Figure 4, Figure 5).
71-year-old man with ruptured epidermal cyst. Photomicrograph (H and E, x200) shows chronic active inflammation with foreign body type giant cells characteristic of granulomatous reaction to ruptured epidermal cyst.
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The one, which exhibited positive radiotracer accumulation, appeared to be a ruptured epidermal cyst with prominent surrounding granulomatous inflammation (Figure 4, Figure 5).