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Файл:Ординатура / Хирургия / Библиотека им академика М.И. Перельмана / Книга_5765_Библиотеки_им_академика_М_И_Перельмана.pdf
3.1 Cystic Lesions
39
b
c
Fig. 3.3 (Continued)
40
3 Ultrasound ofCommon Non-vascular Benign Cutaneous Lesions
a
b
Fig. 3.4 Total rupture of epidermal cyst. (a) Clinical photograph of the
lesion in the right cheek. (b and c) Ultrasound of the right cheek shows
an ill-dened dermal and hypodermal hypoechoic and anechoic struc-
ture with lacunar areas and posterior acoustic reinforcement (b,
greyscale; c, color Doppler; transverse views). On color Doppler (c),
notice the hypervascularity in the periphery of the cyst. See Video 3.2.
3.1 Cystic Lesions
Fig. 3.4 (Continued)
41
c
Fig. 3.5 “Onion-layer” pattern
of epidermal cyst. Notice the
hyperechoic layers (arrowheads),
which correspond to a pack of
compressed layers of keratin
within the cyst.
42
3 Ultrasound ofCommon Non-vascular Benign Cutaneous Lesions
Fig. 3.6 “Pseudotestes” pattern of epidermal cyst. This well-dened,
oval-shaped, hypoechoic structure in the anterior aspect of the thoracic
wall presents a sonographic shape similar to a testicle, but epidermal
cysts tend to be more heterogeneous, owing to the mix of keratin and
cholesterol crystals.
3.1 Cystic Lesions
43
3.1.1.4 Tip
For diagnosing epidermal cysts look for the posterior acoustic reinforcement artifact.
3.1.2 Trichilemmal Cyst
3.1.2.1 Denition
A cyst derived from the external sheath of the hair follicle
without a granular layer. These are commonly found in the
scalp but can be present in other body regions. Frequently,
these cysts clinically show focal sites of alopecia. They can
be single or multiple and can become inamed and then rupture, with a spread of the content in the vicinity. Rarely, they
can present epithelial proliferation, keratinization, some
atypical cells, and a locally aggressive behavior; the latter
forms of presentations are called proliferating or malignant
trichilemmal cysts [2, 6–8].
3.1.2.2 Synonyms
Pilar cyst, isthmus-catagen cyst.
3.1.2.3 Key Sonographic Signs
• Well-dened, round or oval, dermal and/or hypodermal
structure with inner echoes or debris and posterior acoustic reinforcement. Sometimes, these can show hyperechoic calcium deposits and/or hyperechoic linear
structures, which correspond to fragments of hair tracts or
keratin layers (Figs.3.7, 3.8, and 3.9).
• Scalp location is the most common.
• On color Doppler, increased vascularity may be detected
in the periphery of the lesions due to inammation.
However, the center of the cyst is usually avascular.
• Signs suggestive of proliferative or malignant transformation:
non-scalp location, fast growth, lesion greater than 5cm, illdened or lobulated contour, inner hypoechoic solid nodules,
and hypervascularity within the lesion [2, 7, 8].
a
Fig. 3.7 Trichilemmal cyst. (a) Clinical photograph. (b) Ultrasound
(greyscale; transverse view) shows a 10.6-mm (transverse) × 7.7-mm
(thickness) well-dened, round-shaped, anechoic dermal and hypodermal
structure with echoes and posterior acoustic reinforcement artifact in the
scalp region. Notice the hair tracts on the skin surface (marked with arrows
in b). (c) Color Doppler demonstrates lack of vascularity within the lesion.
44
3 Ultrasound ofCommon Non-vascular Benign Cutaneous Lesions
b
Fig. 3.7 (Continued)
c
3.1 Cystic Lesions
45
a
b
Fig. 3.8 Trichilemmal cyst. (a) Clinical image. (b) Ultrasound
(greyscale, longitudinal view, left parietal region) shows an 11.8-mm,
well-dened, oval-shaped, anechoic structure with prominent echoes
due to debris and posterior acoustic reinforcement artifact. (c) Color
Doppler demonstrates hypervascularity at the periphery of the cyst due
to inammation. (d) 3D reconstruction of the lesion.
46
3 Ultrasound ofCommon Non-vascular Benign Cutaneous Lesions
c
Fig. 3.8 (Continued)
d
3.1 Cystic Lesions
47
a
b
Fig. 3.9 Trichilemmal cyst. (a) Clinical photograph. (b) Ultrasound
(greyscale, transverse view, occipital region) shows a well-dened,
oval-shaped, dermal and hypodermal structure that contains multiple
hyperechoic lines that correspond to keratin layers. Notice the poste-
rior acoustic reinforcement artifact at the bottom of the lesion, suggestive of a uid-lled structure. (c) Color Doppler presents increased
vascularity in the periphery of the lesion. (d) 3D reconstruction of the
lesion.
48
3 Ultrasound ofCommon Non-vascular Benign Cutaneous Lesions
c
d
Fig. 3.9 (Continued)