Article Figures & Data
Figures
- fig 1.
Case 1: 75-year-old man with malignant proliferating trichilemmal tumor.
A, Axial T1-weighted MR image shows a poorly defined soft-tissue mass in the central portion of the lower lip. The signal intensity of the mass is comparable to that of the adjacent muscles.
B, On axial T2-weighted MR image, the mass becomes hyperintense with some portions being much higher in signal intensity. The irregular margin of the mass and its infiltrating nature through the orbicularis oris muscle are better seen on the T2-weighted image.
C, Axial contrast-enhanced T1-weighted MR image shows significant enhancement of the mass, with considerable portions remaining unenhanced (fig 1C and D). The areas of the tumor showing no enhancement appear larger on the contrast-enhanced image than on the T2-weighted image.
D, Photograph of a cut section shows partially poorly defined, lobulated, soft-tissue mass, which has a large irregular central cavity. The continuity of the mass with the overlying epidermis (arrow) is a general feature of a tumor of hair sheath origin.
E, Photomicrograph shows numerous proliferating lobules of reserve cells with extensive trichilemmal keratinization (hematoxylin-eosin, original magnification ×20).
F, Higher-magnification photomicrograph shows dysplastic cells with high nuclear-to-cytoplasmic ratios, nuclear pleomorphisms, and frequent mitoses. There is no evidence of a granular layer associated with keratinization, which is a useful feature for distinguishing PTT from squamous cell carcinoma (hematoxylin-eosin, original magnification ×200).
- fig 2.
Case 2: 54-year-old woman with coexistent proliferating trichilemmal tumor and trichilemmal cyst.
A, Axial contrast-enhanced CT scan at level of the submandibular glands shows a large, well-encapsulated, cystic mass located in the subcutaneous fat of the left posterior part of the neck. It has a well-enhancing wall of variable thickness, which contains numerous speckled calcifications. Note a focal area of smooth soft-tissue elevation (arrow) from the anterior wall of the mass. There were several similar foci of soft-tissue elevations in the inner wall of the mass (not shown). The outer portions of the mass abut the overlying skin. Although the lesion apparently reveals a mass effect on the adjacent paravertebral muscles, the fatty interface is seen to be well preserved.
B, Photograph of a cut section corresponding to A shows a well-encapsulated, unilocular, cystic mass continuous with the overlying epidermis (arrowhead). There is a focal, smooth excrescence of soft-tissue (arrow) in the deep portion of the inner wall.
C, Photomicrograph of soft-tissue portion of the mass shows extensive areas of trichilemmal keratinization without formation of a granular layer. The reserve cells reveal differentiation toward large polygonal keratinocytes (hematoxylin-eosin, original magnification ×200).
