Ductal carcinoma in situ in a benign phyllodes tumor of breast: A rare presentation.

Phyllodes tumor (PT) is an uncommon tumor of female breast. The tumor clinically, radiologically, cytologically as well as histologically can mimic fibroadenoma which is a common tumor of fibroepithelial group. Ductal carcinoma in situ (DCIS) in the epithelial component of PT is very rare. We report a rare case of intermediate grade DCIS arising in a benign PT in a 42-year-old lady. The patient presented with a small nodule in right breast along with serosanguineous discharge from nipple. Ultrasonography and cytology failed to distinguish between fibroadenoma and PT. Histopathological examination following wide local excision displayed the biphasic tumor comprising of benign looking cellular stroma and epithelial lining. It also demonstrated the foci of intermediate grade DCIS without any invasive component. Considering the clinicoradiological profile along with histopathological features, the diagnosis of DCIS in a benign PT of breast was made.

INTRODUCTION

Phyllodes tumors (PTs) of breast are a group of circumscribed biphasic fibroepithelial tumors characterized by an epithelial component arranged in clefts surrounded by a hypercellular mesenchymal component that is typically organized in a leaflike pattern.[1] PTs account for 0.3-1% of all primary tumors of the breast and for 2.5% of all fibroepithelial tumors of the breast.[2] These lesions generally occur in an older age group than fibroadenomas; most patients are middle-aged or elderly.[3] PTs are highly variable in their gross appearance, but majority of them display a solid, fleshy mass with cystic areas. The tumors may be small or very large, ranging in size from 1 to 45 cm.[1] The epithelial abnormality rarely reaches a level acceptable as intraductal carcinoma, and the diagnosis of intraductal or invasive duct carcinoma in PTs is infrequent.[4] Like mammary epithelial cells in other locations, those composing the glands of a PT can give rise to atypical epithelial hyperplasia and carcinoma; however, experience has shown that, unlike fibroadenomas, which occasionally harbor carcinoma, PTs rarely do so.[5] We report a very unique case of ductal carcinoma in situ (DCIS) occurring within a benign PT in a 42-year-old woman.

CASE REPORT

A 42-year-old multiparous woman presented with 1.5-year history of a small nodule in her right breast. She also complained of serosanguineous discharge from nipple. On clinical examination; the mass was firm, nontender, well-defined, and mobile. No skin change over the mammary region or nipple retraction was noted. Clinically, her left breast was found to be normal. There was no palpable lymph node in the axillary or supraclavicular region. Ultrasonography (USG) of the mammary gland [Figure 1a] revealed a 1.1 cm × 0.62 cm × 0.4 cm hypoechoic heterogeneous solid mass with regular border without any calcification. Abdominal and pelvic computed tomography (CT) and USG, chest imaging, complete blood count and biochemical tests (liver function tests, and alkaline phosphatase) were all normal. However, her erythrocyte sedimentation rate (ESR) was raised (68 mm at the end of 1 hour). Fine needle aspiration smear revealed a moderately cellular lesion, comprising primarily of benign looking plump stromal cells along with few small clusters of mildly atypical ductal epithelial cells. Mitotic figures were infrequent. However based on cytology alone, no definite distinction was possible between PT and fibroadenoma. Considering the patient's age, history of serosanguineous discharge, and cytological features, the patient was planned for a wide local excision of the mass. The mass was received in the department of pathology. Grossly, the mass measured 2.2 cm × 1.2 cm × 0.8 cm and appeared well circumscribed, firm, and fleshy. The cut surface revealed greyish white lobulated mucoid areas [Figure 1b]. Areas of hemorrhage, necrosis, and small cyst were also noted. Histopathological examination demonstrated a well circumscribed mass, showing biphasic morphology comprising of epithelial component and cellular spindle stroma. Most of the areas characteristically revealed compressed glands displaying a well-developed leaflike projections protruding into dilated spaces [Figure 2a]. The moderately cellular stroma was formed by monomorphic spindle cells with minimal atypia having low mitotic count (<5/10 high power fields [HPF]) without any heterologous stromal differentiation. Areas of hyalinization and myxoid change were also noted. The epithelial component in most of the areas was morphologically benign. However, some of the areas definitely displayed features of DCIS without any features of stromal invasion [Figure 2b]. DCIS areas [Figures 2c and d] revealed moderately atypical poorly polarized cells with inconspicuous nucleoli, coarse clumped chromatin, moderately increased nuclear-cytoplasmic ratio producing cribriform and solid patterns without any necrosis and calcification. Considering the patient's clinicoradiological profile and most importantly histopathological findings, the diagnosis of intermediate grade DCIS arising in a case of benign PT was arrived at.

Figure 1

(a) Ultrasonography of the right breast nodule showing hypoechoic heterogeneous solid mass with regular borders, (b) Gross features of the breast mass after wide local excision. (1 = Necrohemorrhagic area, 2 = well circumscribed greyish fleshy white mass with mucoid surface, 3 = small cyst, 4 = prominent nodular area)

Figure 2

(a) Classical leaflike areas in a benign phyllodes tumor (H and E, ×40), (b) Benign phyllodes tumor and ductal carcinoma (DCIS) in a same scanner field (H and E, ×40), (c and d) Intermediate grade DCIS showing cribriform and solid pattern (H and E, ×400)

DISCUSSION

When the preoperative clinical findings are suggestive of fibroadenoma, the tumor can be shelled out from the breast, but it is preferable to include at least a thin rim of surrounding normal breast to minimize the need for reexcision in rare instances when the lesion proves to be a PT. PTs are classified into benign, borderline, and high grade malignant categories. The distinction among these three subgroups is based on the combination of histologic characteristics of the tumors and is predictive of the probable clinical course.[4] To minimize the future chances of recurrence in a suspected case of PT, the patient of the present report had undergone wide local excision instead of enucleation as done mostly in fibroadenoma. Recent WHO classification[2] on breast tumors clearly stated that any PT that has recognizable epithelial elements may harbor DCIS, lobular neoplasia, and their invasive counterparts. But this is a relatively rare finding.

Nomura and colleagues[6] reported a noninvasive ductal carcinoma arising in malignant PT in a 75-year-old lady. Korula et al.,[7] described a case of malignant PT with intraductal and invasive carcinoma and lymph node metastasis. Macher-Goeppinger and coworkers[8] reported a case of high grade invasive ductal breast cancer within a malignant PT in a 70-year-old woman. Kuo and colleagues[9] described a case of invasive ductal carcinoma in a borderline PT with isolated carcinoma cells in the sentinel lymph node of a young woman. Neto et al.,[10] noticed an interesting case of synchronous coexistence of benign PT in one breast and invasive carcinoma in the other breast in a 66-year-old multiparous lady. However, reported cases of benign PT with invasive or noninvasive ductal carcinoma are much rarer. In situ and invasive carcinoma within a benign PT associated with lymph node metastases was observed by Parfitt et al.,[11] Nio and coworkers[12] described a case of DCIS arising within a benign PT in a 53-year-old female.

Similarly, our case is one of those rare cases showing features of DCIS in a case of PT.