|Year : 2015 | Volume
| Issue : 3 | Page : 404-406
Extensive squamous metaplasia in a benign phyllodes tumor: A rare case report
Harsh Kumar, Mohamad Banyameen Iqbal, Archana Buch, Narayanan Panicker
Department of Pathology, Dr. D.Y. Patil Medical College and Research Center, Pimpri, Pune, Maharashtra, India
|Date of Web Publication||15-May-2015|
Mohamad Banyameen Iqbal
Department of Pathology, Dr. D.Y. Patil Medical College and Hospital, Pimpri, Pune, Maharashtra
Source of Support: None, Conflict of Interest: None
Phyllodes tumors (PTs) with extensive squamous metaplasia is an uncommon biphasic fibroepithelial neoplasms of breast, comprising of <1% of all breast neoplasm's. In this article, we report a case of a 55-year-old female patient admitted to the General Surgery Department with a rapidly enlarging, palpable mass in right breast. After histopathological examination, it was diagnosed to be as benign PT with extensive squamous metaplasia. Metaplastic changes are known, but infrequent in these tumors. Extensive squamous metaplasia within PT is rare and may occur in benign, borderline and malignant subtypes. There are only a few cases reported in the literature. We therefore, aimed to present this case in view of its extremely rare nature.
Keywords: Benign breast tumours, phyllodes tumour, squamous metaplasia
|How to cite this article:|
Kumar H, Iqbal MB, Buch A, Panicker N. Extensive squamous metaplasia in a benign phyllodes tumor: A rare case report. Med J DY Patil Univ 2015;8:404-6
| Introduction|| |
Phyllodes tumors (PTs) are uncommon fibroepithelial lesions.  They make up 0.3-0.5% of female breast tumors  and have an incidence of about 2.1/million, the peak of which occurs in women aged 45-49 years. , The tumor is rarely found in adolescents and the elderly. They have been documented as early as 1774, as a giant type of fibroadenoma.  Chelius  in 1827 first described this tumor. Johannes Muller (1838) was the first person to use the term cystosarcoma phyllodes for these tumors. It was believed to be benign until 1943, when Cooper and Ackerman reported on the malignant biological potential of this tumor. In 1981,  the World Health Organization adopted the term PT and as described by Rosen the tumor was subclassified by them histologically as benign, borderline, or malignant according to features such as tumor margins, stromal overgrowth, tumor necrosis, cellular atypia, and number of mitosis per high power field.  The majority of PTs have been described as benign (35-64%), with the remainder divided between the borderline and malignant subtypes. Metaplastic changes may be observed in these tumors in the epithelial or stromal components. The stroma may show cartilaginous, osteoid, or lipomatous metaplasia, while epithelium may occasionally show apocrine or squamous metaplasia. Rarely, ductal or lobular carcinoma in situ, invasive carcinoma may arise in the epithelial component.  Herein, we present a case of benign PT with extensive squamous metaplasia.
| Case Report|| |
We report a case of a 55-year-old female admitted in the General Surgery Department with a history of rapidly enlarging, palpable mass in right breast of 6 months duration. Physical examination showed a palpable, well-defined mobile mass measuring approximately, 10 cm × 8 cm × 5 cm in diameter. It was not fixed to the surrounding soft tissue or the overlying skin. Fine-needle aspiration cytology and breast ultrasound had been performed and offered a differential diagnosis of benign phyllodes tumor versus an epidermal cyst. On examination, her general condition was good, she was afebrile. Her general and systemic examination was within the normal limits. Local examination revealed a firm, large mobile swelling involving the breast; it was tender to touch and had been progressively increasing in size. The mass was excised and sent for histopathological examination.
The excised specimen measured 11 cm × 10 cm × 6 cm. It was encapsulated; the cut section showed numerous well-defined grey white nodules measuring 3-5 mm in diameter [Figure 1]. One area showed a cystic cavity with leaf like mass projecting inside.
|Figure 1: Gross morphology of benign phyllodes tumor showing numerous cyst like spaces|
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Multiple sections were taken, processed and analyzed. The periphery of the tumor was well defined. The multiple cysts observed on gross examination contained keratin flakes, and were lined by benign stratified squamous epithelium [Figure 2] and [Figure 3]. The stroma in between the cysts was moderately cellular and consisted of benign spindle cells [Figure 4] with many foci of squamous metaplasia. Some areas of the tumor showed gland like structures lined by a double layer of epithelium lying in a spindle cell stroma. These areas were reminiscent of fibroadenoma. The stroma was benign throughout the tumor with no mitotic figures. No other metaplastic elements were seen.
|Figure 2: Squamous metaplasia within benign phyllodes tumor: Presence of cystic spaces filled with keratin material (H and E, ×100)|
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|Figure 3: Sections showing benign spindle cell stroma between keratin cysts (H and E, ×200)|
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|Figure 4: Sections of the cyst wall lined by benign stratified squamous epithelium (H and E, ×400)|
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| Discussion|| |
Phyllodes tumors are an uncommon fibroepithelial neoplasm of the breast. It may grow rapidly and create observable asymmetry of the breast.  These tumors are usually not aggressive. Classically, the patients present with large mobile rapidly growing mass having smooth borders. On histopathological examination, the characteristic findings of PTs include a hypercellular spindle cell stroma having gland like structures reminiscent of an intracanalicular growth pattern.  The cleft-like glandular spaces are lined by two layers of cells, with the epithelium towards the inside and myoepithelial cells outward. PT is usually classified as benign, borderline or malignant, according to histologic features, which is decided by cellularity, stromal overgrowth, margin status and mitotic figure count in the stromal cells. ,,, One of the most commonly used parameter in classifying PT is mitotic figure counts.  If the mitotic count is <4/10 HPF, the tumor is classified as benign, however if there are >10 mitoses/10 HPF, it is considered as having a malignant potential. The borderline PT represents intermediate microscopic findings.  In our case, no mitotic figures were observed, suggesting a benign subtype. In the stromal and epithelial components of PT metaplastic changes may occur, but are uncommon. In one of the reported PT series, the patterns of stromal metaplasia observed included adipose and chondromyxoid elements. Malignant heterologous components, such as osteosarcoma, rhabdomyosarcoma and liposarcoma was presented in 11 (3.3%) of 335 cases. The epithelial component may show a variety of appearances. Varying degrees of usual-type epithelial hyperplasia is well recognized, and epithelial squamous metaplasia has been observed in 12 cases (3.6%), 5 of which had revealed squamous cysts.  Apocrine metaplasia has also been reported in the epithelium of PTs. , Squamous metaplasia of ductal epithelium, which may occur in benign, malignant and borderline PTs, has been found in about 10% of PTs.  Examination of cystic areas of squamous metaplasia by aspiration cytology may lead to a mistaken diagnosis of a squamous cyst  as has happened in our case. Excluding PTs, extensive squamous metaplasia in breast as much as observed in our case has been reported only in gynecomastia  and benign breast papillomatosis.  The squamous change in the breast has been suggested to begin within the myoepithelial cell layer, before eventually involving the entire acinus. , This myoepithelial origin of the metaplastic squamous cells has been supported by the immunohistochemical studies, which showed expression of actin, vimentin and S-100 protein in the metaplastic squamous cells.  In conclusion, extensive cystic squamous metaplasia is a rare feature in PTs.
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[Figure 1], [Figure 2], [Figure 3], [Figure 4]