AJR 2005; 184:S47-S48
© American Roentgen Ray Society
Concentric Rings Within a Breast Mass on Sonography: Lamellated Keratin in an Epidermal Inclusion Cyst
Pavel Crystal1 and
Ruthy Shaco-Levy2
1 Department of Radiology, Soroka University Medical Center, Faculty of Health
Sciences, Ben Gurion University of the Negev, P.O. Box 151, Beer-Sheva 84105,
Israel.
2 Department of Pathology, Soroka University Medical Center, Faculty of Health
Sciences, Ben Gurion University of the Negeva, Beer-Sheva 84105, Israel.
Received March 3, 2004;
accepted after revision May 21, 2004.
Address correspondence to P. Crystal
(pcrystal{at}bgumail.bgu.ac.il).
Introduction
Epidermal inclusion cyst of the breast is a rare and benign
condition. We present such a case with alternating hypoechoic and hyperechoic
concentric rings. This onion-ring appearance has not been previously described
on breast sonography and corresponds well to the pathologic features of
epidermal inclusion cysts, which contain lamellated keratin.
Case Report
A 65-year-old woman was referred for evaluation of a movable lump in her
left breast. Mammography revealed an oval, dense, smoothly outlined mass
(Fig. 1A). Breast sonography
was ordered for further evaluation. A sonographic examination was performed
with an HDI 5000 system (Philips Medical Systems) and a broadband 5- to 12-MHz
linear array transducer. Sonography showed an ovoid, heterogeneously
hypoechoic mass with alternating hypoechoic and hyperechoic concentric rings
(Fig. 1B). The lesion had
well-demarcated borders and through-transmission. No color flow signal was
detected inside the lesion. Extension of the mass into the dermis was
observed, and a cutaneous origin was suggested.
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Fig. 1B. —65-year-old woman with epidermal inclusion cyst of left
breast. Sonography shows solid, heterogeneously hypoechoic mass with
alternating hypoechoic and hyperechoic concentric rings that look like onion
rings.
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Because of the patient's anxiety and request, sonography-guided core needle
biopsy of the lesion was performed (Fig.
1C). Pathologic examination revealed mature squamous epithelium
and multiple layers of keratin (Fig.
1D), consistent with an epidermal inclusion cyst.
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Fig. 1C. —65-year-old woman with epidermal inclusion cyst of left
breast. Postfire sonogram after sonography-guided core biopsy shows echogenic
14-gauge needle has traversed lesion. Alternating hyperechoic and hypoechoic
rings are visualized in mass.
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Fig. 1D. —65-year-old woman with epidermal inclusion cyst of left
breast. On photomicrograph, lesion is lined by epidermal-type epithelium
(arrowhead) and contains abundant lamellated keratin
(arrows) pathognomonic for epidermal inclusion cyst. (H and E
x200)
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Discussion
Epidermal inclusion cysts are formed by inclusion of keratinizing squamous
epithelium within the dermis, resulting in a cyst filled with lamellated
keratin. These common benign lesions can occur anywhere but are most often
found on the face, trunk, and neck. Neoplastic transformation within epidermal
inclusion cyst is very rare.
Fewer than 40 cases of epidermal inclusion cyst of the breast have been
reported in the English-language literature
[1-8].
Typical epidermal inclusion cysts appear as smooth, round nodules attached to
the skin. It is not uncommon for breast epidermal inclusion cysts to be
clinically misdiagnosed initially
[1]. They usually appear as
well circumscribed on mammography and solid on sonographic examination. Even
when the mammographic appearance of a palpable mass is consistent with a
benign lesion, the finding of a solid lesion on sonography may result in the
need for a tissue diagnosis to exclude a carcinoma with well-defined
borders.
The sonographic appearance of breast epidermal inclusion cysts has been
described as solid, circumscribed, and complex
[3-6].
Denison et al. [5] describe
specific sonographic features of breast epidermal inclusion cysts in their
report of cysts with extension into the dermis.
An onion-ring appearance with alternating concentric hyperechoic and
hypoechoic rings has been described in epidermoid cysts of the testis
[9,
10], which also contain
multiple layers of keratin.
Resolution of current sonography equipment allowed identification of the
onion-ring pattern. The management of an epidermal inclusion cyst depends on
its presentation. Asymptomatic lesions do not have to be treated, and a biopsy
of a nonpalpable lesion with sonographic features of an epidermal inclusion
cyst may be unnecessary. In the case of palpable lumps in the breast, patients
are often concerned and may request a biopsy, as in the present case. Some
authors recommend an excision to avoid the risk of a malignant change
[7].
In conclusion, we described the onion-ring pattern on sonography in an
epidermal inclusion cyst of the breast.
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Introduction
Case Report
