Letter to the Editor
Ultrasound B-mode and elastographic findings of mixed tumour of the skin on the scalp
Article first published online: 29 JUL 2014
© 2014 European Academy of Dermatology and Venereology
Journal of the European Academy of Dermatology and Venereology
Volume 30, Issue 1, pages 153–155, January 2016
How to Cite
Imafuku, K., Hata, H., Kitamura, S., Iwata, H. and Shimizu, H. (2016), Ultrasound B-mode and elastographic findings of mixed tumour of the skin on the scalp. Journal of the European Academy of Dermatology and Venereology, 30: 153–155. doi: 10.1111/jdv.12644
- Issue published online: 23 DEC 2015
- Article first published online: 29 JUL 2014
Mixed tumour of the skin (MTS) is a relatively rare adnexal tumour usually presenting as a slow-growing, painless nodule in the head and neck region, particularly often around the nose, cheek and upper lip.[1, 2] When MTS occurs on the scalp, it may be difficult to clinically differentiate MTS from other tumours, including epidermal cyst, which often develops on the scalp. Although ultrasonography has been utilized broadly as a non-invasive diagnostic tool for skin tumours, to the best of our knowledge, there have been no reported MTS cases with ultrasonographic information including elastographic features in the medical literature. Here, we show the elastographic findings of MTS, which clearly distinguish from epidermal cyst.
A 54-year-old woman was referred to our hospital because of a tumour on the top of her scalp. She had noticed the lesion 6 months before the referral. As clinical manifestations, a well-defined elastic hard subcutaneous tumour of 10 mm in diameter was observed (Fig. 1a). The patient underwent ultrasound scanning with the HI VISION 900 (Hitachi Medical Corporation, Tokyo, Japan). A conventional linear probe with a 5- to 13-MHz transducer was used in all scans, including B-mode, colour Doppler test and elastography. In all elastographic examinations, we used ‘quasi-static strain imaging’, which indicates slight probe compression towards the tumour, in order to estimate elasticity precisely.[3, 4]
Ultrasonography (B-mode) revealed the border to be subglobular, smooth and well circumscribed, the inside of the tumour to be heterogeneous and high-echo, and posterior echo enhancement to be evident (Fig. 2a; red arrowhead).
Colour Doppler test showed the inside and periphery of the tumour to be hypovascular. Ultrasound elastography indicated that the tumour interior was island-shaped, with a soft, elastic cord-like portion (red) (Fig. 2a; white arrowhead) mixed in a background of moderately (green). Histopathology specimens showed a subcutaneous tumour with an intimate admixture of epithelial–myoepithelial structures within a chondromyxoid and fibrous stroma (Fig. 1b,c). Decapitation secretion was occasionally seen in the space (Fig. 1d). No cellular atypia was seen, and only occasional mitoses were found. From these findings, the diagnosis of MTS was made. Retrospectively, the elastic moderate lesion (visualized green in Fig. 2a) demonstrated in elastography may pathologically correspond to closely aggregated myoepithelial cells around the sweat gland. The elastic soft lesion (visualized in yellow to red in Fig. 2a) that was revealed in elastography may be histologically comparable to a broadly mucinous region, empty space and the chondroid portion.
To compare the present case with ordinary epidermal cyst, we presented five images of cases that had already been histologically confirmed as epidermal cyst. Ultrasonography (B-mode) of epidermal cyst revealed the tumour to be well circumscribed, the inside of the tumour to be a heterogeneous high-echoic region, posterior echo enhancement to be evident (Fig. 2b–f; blue arrowhead) and lateral shadow to be seen (Fig. 2b–f; red arrowhead).[5-8] Almost of all these findings of epidermal cysts were extremely similar to the B-mode image of MTS.
On the other hand, elastography of epidermal cysts uniformly visualized the inside of the tumour as blue or green (Fig. 2b–f; yellow arrowhead), finding that were completely different from the MTS image of our own case (Fig. 2a).
In our case, the combination of B-mode and elastographic findings helped us to keep cystic lesion in mind as a differential diagnosis. When similar elastographic findings for MTS of the scalp are accumulated, it may become more easily diagnosable. We should be encouraged to examine skin tumours on the scalp in conjunction with elastography to make better clinical diagnoses.
- 1Chondroid syringoma. Arch Dermatol 1961; 84: 835–847., .
- 2Mummified cutaneous mixed tumor. Arch Dermatol 1975; 111: 194–196., , .
- 3Ultrasound elastography: principles and techniques. Diagn Interv Imaging 2013; 94: 487–495., , et al.
- 4Imaging the mechanical stiffness of skin lesions by in vivo acousto-optical elastography. Opt Express 2006; 14: 9770–9779., , et al.
- 5High-resolution ultrasonography in superficial soft tissue tumors. J Med Ultrasound 2007; 15: 152–174., , et al.
- 6Epidermal cyst of the breast treated by vacuum-assisted biopsy. Int Surg 2007; 98: 65–69., , et al.
- 7Penile epidermal cyst in a patient with augmentation penoplasty. Korean J Urol 2013; 54: 207–208., , et al.
- 8Differences in sonographic features of ruptured and unruptured epidermal cysts. J Ultrasound Med 2012; 31: 265–272., , et al.