Clinical Imaging 33 (2009) 311–313

Case reports

Radiology pathology conference of Brooke Army Medical Center:trichoblastoma of breast☆

Steven Craiga,⁎, Liem T. Bui-Mansfielda,b, Joanna D. Luskc

aDepartment of Radiology, Brooke Army Medical Center, San Antonio, TX 78234, USAbDepartment of Radiology, Wake Forest University, Winston-Salem, NC 27157-1088, USAcDepartment of Pathology, Brooke Army Medical Center, San Antonio, TX 78234, USA

Received 28 October 2008; accepted 8 January 2009

Abstract

The differential diagnosis of a superficial breast lesion detected on mammography typically includes seborrheic keratosis, dermal nevus,epidermal inclusion cyst, and basal cell carcinoma with subcutaneous invasion [Kopans DB. Breast Imaging. 3rd ed. Philadelphia: LippincottWilliams & Wilkins; 2007; pp. 481-2]. The case presented is of a trichoblastoma of the superficial breast. Trichoblastoma is a benign skinneoplasm that is rarely found in the breast. It has not previously been described in the radiologic literature. This case describes and correlatesthe findings of trichoblastoma of the breast on mammography, sonography, and histology.Published by Elsevier Inc.

Keywords: Trichoblastoma; Breast mass; Mammography; Sonography; Ultrasound

1. Case report

A 60-year-old woman presented with a 10-year history ofa superficial left breast mass. Physical exam revealed apainless palpable lump in the lower inner quadrant of the leftbreast. There was no visible skin lesion, skin thickening, ornipple retraction. On mammogram, the breasts were fattyreplaced bilaterally without architectural distortion, spicula-tion, or microcalcifications (Fig. 1A and B). A 1-cmhomogeneous, well-circumscribed mass was seen in thelower inner quadrant of the left breast. Sonography of the leftbreast showed a 9×9×6-mm, well-defined hypoechoichomogeneous mass which communicated with the dermisof the skin and without distal acoustic enhancement orshadowing (Fig. 1C). Excisional biopsy was performed.

☆ The opinions and assertions contained herein are those of the authorsand should not be construed as official or as representing the opinions of theDepartment of the Army or the Department of Defense.

⁎ Corresponding author. 831 Tiger Lily, San Antonio, TX 78260, USA.Tel.: +1 210 916 3290 (Voice), +1 240 644 9125 (Cell); fax: +1 210 916 5193.

E-mail address: steven.craig@amedd.army.mil (S. Craig).

0899-7071/09/$ – see front matter. Published by Elsevier Inc.doi:10.1016/j.clinimag.2009.01.007

On gross examination, the lesion was a nonencapsulatedfragment of tan-yellow subcutaneous fibroadipose tissueattached to light brown skin. Sectioning of the fibroadiposemass revealed a white-tan homogeneous cut surface.Microscopic examination revealed a nodular, circumscribedproliferation of nests of basaloid cells located in thedermis, with extension into the subcutis. Examinationunder higher power revealed irregular nests of basaloidcells with focal abortive hair follicle development andscant intervening stroma (Fig. 1D). These findingsextended to the edges of the biopsy, which did not containepidermis. The histologic findings were consistent withtrichoblastoma. These lesions do not, however, typicallyshow epidermal connection.

2. Discussion

The differential diagnosis of a superficial breast lesiondetected on mammography includes seborrheic keratosis,dermal nevus, epidermal inclusion cyst, and basal cellcarcinoma with subcutaneous invasion [1].

Fig. 1. Images of the breast of a 60-year-old woman with a 10-year history of left superficial breast mass. (A and B) Cranial-caudal and mediolateral obliquediagnostic mammogram of the left breast show a well-circumscribed mass in the lower inner quadrant (triangular marker). (C) Sonography reveals a well-defined hypoechoic mass arising from the dermis (arrow) and extending into subcutaneous fat (T) without distal acoustic enhancement or shadowing.(D) Photomicrograph (H&E stain, 40×) showing irregular nests of basaloid cells (arrow) with focal abortive hair follicle development (f) and scantintervening stroma (S).

312 S. Craig et al. / Clinical Imaging 33 (2009) 311–313

Trichoblastoma is a rare benign skin neoplasm of hairstructures first described by Headington [2] in 1970. It is aslow-growing tumor with an increased incidence in thesixth to seventh decade. It presents clinically as a solitary,nonulcerated, skin colored to brown or blue papule ornodule. Trichoblastoma is commonly mistaken for basalcell carcinoma or dermal nevi, most commonly on thescalp and face, and occasionally in the extremities andtrunk of adults. Trichoblastoma in the skin of the breast isexceedingly rare [3].

Headington [2] originally described a group of benignsubcutaneous neoplasms with several different histologicpatterns. He named these neoplasms according to theirmorphologic characteristics. For simplicity, Ackerman [4]grouped these lesions into one diagnosis called trichoblas-

toma. These lesions are characterized by multiple dermal orsubcutaneous, smooth-bordered clusters of germinativecells. There are typically several foci of immature follicularpapillae and germ cells. The epithelial clusters aresurrounded by sclerotic or partly hyalinized stroma.

In 1998, Ogata [5] described the CT and MR appearanceof trichoblastoma in the upper arm which mimicked a softtissue sarcoma. However, the mammographic and sono-graphic appearance of trichoblastoma has not been reported.On sonography, the mass extended from the dermis, whichwas confirmed histologically.

Surgical excision is the preferred treatment of trichoblas-toma because it is both diagnostic and therapeutic.Recurrence is common if resection is not complete; however,malignant transformation is rare.

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References

[1] Kopans DB. Breast Imaging. 3rd ed. Philadelphia: Lippincott Williams& Wilkins, 2007. pp. 481–2.

[2] Headington JT. Differentiating neoplasms of hair germ. J Clin Pathol1970;23:464–71.

[3] Shimazaki H. Trichoblastoma of the skin occurring in the breast. A casereport. Acta Cytol 2001;45:435–40.

[4] Ackerman AB. Neoplasms With Follicular Differentiation. Philadel-phia: Lea & Fibiger, 1993. pp. 94–101.

[5] Ogata T. Giant trichoblastoma mimicking malignancy. Arch OrthopTrauma Surg 1999;119:225–7.