Synchronous collision tumor of malignant phyllodes and invasive ductal carcinoma

Usha K. N Pai; Alfie J Kavalakat; Nikita Thomas

doi:10.4103/oji.oji_11_22

CASE REPORT

Year : 2022 | Volume : 6 | Issue : 3 | Page : 78-81

Synchronous collision tumor of malignant phyllodes and invasive ductal carcinoma

Usha K. N Pai¹, Alfie J Kavalakat², Nikita Thomas¹
¹ Department of Pathology, Jubilee Mission Medical College and Research Institute, Thrissur, Kerala, India
² Department of Surgery, Jubilee Mission Medical College and Research Institute, Thrissur, Kerala, India

Date of Submission	11-Apr-2022
Date of Decision	12-Aug-2022
Date of Acceptance	28-Nov-2022
Date of Web Publication	21-Dec-2022

Correspondence Address:
Usha K. N Pai
Department of Pathology, Jubilee Mission Medical College and Research Institute, Thrissur - 680 005, Kerala
India

Source of Support: None, Conflict of Interest: None

DOI: 10.4103/oji.oji_11_22

Abstract

Phyllodes tumor (PT) constitutes <1% of breast tumors. Malignancy usually arises from the stromal component forming homologous or heterologous elements such as chondrosarcoma, liposarcoma, fibrosarcoma, osteosarcoma, or rhabdomyosarcoma. Rarely, carcinoma can arise from the epithelial cells within the PT. Rarer is the occurrence of collision tumor of malignant phyllodes and carcinoma in the breast which lacks the exact incidence since only few cases are reported in the literature. This is another such rare case of synchronous collision tumor of malignant phyllodes having chondrosarcomatous and osteosarcomatous differentiation associated with invasive and in situ ductal carcinoma having metastatic carcinomatous deposits in axillary lymph nodes in a 43-year-old female. Hence, extensive sampling of the gross specimen is crucial in diagnosing the collision tumors which are not detected either in breast imaging studies or during the surgery. Since malignant PT usually spreads through a hematogenous route, it has to be treated by wide local excision or simple mastectomy without the axillary lymph node dissection. If a PT is associated with carcinoma, the patient management and prognosis depend on the stage of the carcinoma.

Keywords: Carcinoma breast, collision tumor, malignant phyllodes

How to cite this article:
Pai UK, Kavalakat AJ, Thomas N. Synchronous collision tumor of malignant phyllodes and invasive ductal carcinoma. Oncol J India 2022;6:78-81

How to cite this URL:
Pai UK, Kavalakat AJ, Thomas N. Synchronous collision tumor of malignant phyllodes and invasive ductal carcinoma. Oncol J India [serial online] 2022 [cited 2023 Jun 5];6:78-81. Available from: https://www.ojionline.org/text.asp?2022/6/3/78/364561

Introduction

Phyllodes tumor (PT) is an uncommon fibroepithelial tumor of the breast with mixed epithelial and stromal components and constitutes <1% of breast tumors.^[1] In most cases, malignant PT arises from the stromal component with or without heterologous differentiation such as lipomatous, chondroid, osteoid, or fibrous tissue. Rarely, carcinoma originates from the epithelial component within the PT and accounts for only 1%–2% of all types of phyllodes.^[2],[3],[4] The coexistence of malignant PT and invasive breast carcinoma as two separate tumors in the ipsilateral breast is extremely rare and only few cases have been reported in the literature.^[5],[6] Patient management depends on the individual tumors. Herein, we report a case of synchronous collision tumor with components of malignant phyllodes and invasive ductal carcinoma in a 43-year-old female.

Case Report

A 43-year-old female presented with a left breast lump of two years' duration. A firm lobulated mass was noted on clinical examination involving three-fourths of the left breast. The mammogram showed a large heterogeneous mass in the left breast with cystic spaces and internal vascularity, obscured margins, and pleomorphic calcification and Breast Imaging Reporting and Data System (BI-RADS) score of 4 [Figure 1]. There was no comment on the status of the axillary lymph nodes in the imaging report as well as the clinical findings. The patient gave a history of excision of benign PT in the right breast nine years ago. Core needle biopsy from the left breast mass on histopathology showed features of PT. There were no apparent malignant features in both the epithelial and stromal components.

Figure 1: Mammogram scan showing heterogeneous mass

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A simple mastectomy was planned. However, due to enlarged axillary lymph node at surgery, a left simple mastectomy with only level I left axillary lymph node dissection was performed. Level II lymph nodes were not sampled. The gross specimen revealed a tumor measuring 18 cm × 13 cm × 10 cm [Figure 2]a. The cut section of the tumor was solid, gray-white lobulated with necrosis and myxoid areas. Serial sectioning of the breast revealed another gray-white tumor superiorly 3 cm away and discontinuous from the larger mass measuring 2.5 cm × 2 cm × 2 cm [Figure 2]b, and nineteen axillary lymph nodes were identified [Figure 2]c. Microscopic examination of the gross specimen was performed under hematoxylin and eosin stain and immunohistochemical examination was also performed [Figure 3], [Figure 4], [Figure 5]. Microscopic sections from the larger mass showed a tumor with benign epithelial and stromal components [Figure 3]a. In other areas, there was a lack of epithelial components with stromal overgrowth, increased stromal cellularity, malignant spindle cells with hyperchromatic, pleomorphic nucleus, and many mitoses (>10/10HPF), and necrosis [Figure 3]b and [Figure 3]e. There were large areas with predominantly heterologous chondrosarcoma differentiation and focal area of osteosarcoma component [Figure 3]c, [Figure 3]d, [Figure 3]f and [Figure 3]g. Microscopic sections from the smaller mass showed an invasive tumor composed of malignant ductal epithelial cells arranged in groups, cords, and tubular patterns with a focal area of ductal carcinoma in situ (DCIS) [Figure 4]a, [Figure 4]b, [Figure 4]c. All the nineteen axillary lymph nodes had carcinomatous deposits [Figure 4]d. On immunohistochemical examination, breast carcinoma was negative for estrogen receptor (ER) and progesterone receptor (PR) and positive for HER-2 (score 3), and Ki-67 proliferation index was 32% [Figure 4]e, [Figure 4]f, [Figure 4]g and [Figure 4]h. The intervening breast tissue showed normal histology [Figure 5]. The final diagnosis was high-grade malignant phyllodes having heterologous chondrosarcomatous and osteosarcomatous components associated with invasive ductal carcinoma, Grade 3, DCIS, nuclear Grade 1, and metastatic carcinomatous deposits in all the nineteen (19/19) level I axillary lymph nodes (pT2 pN3a). The patient was referred to the oncology department for further management, but she was lost to follow-up.

Figure 2: Gross specimen showing (a) malignant phyllodes tumor; arrow points to chondrosarcomatous area; (b) arrow indicates invasive ductal carcinoma with DCIS; (c) level I axillary lymph nodes. DCIS: Ductal carcinoma in situ

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Figure 3: Photomicrographs: (a) Benign PT; (b) and (e) MPT with malignant spindle cells; (c) and (f) chondrosarcoma differentiation; (d) and (g) osteosarcoma differentiation

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Figure 4: Photomicrographs: on pathological examination showing features of invasive ductal carcinoma (a and b); DCIS (c); and metastasis in axillary lymph nodes (d); and on immunohistochemistry showing estrogen receptor (ER) negative (e), progesterone receptor (PR) negative (f), HER2 expressed (g), and high Ki-67 (h). DCIS: Ductal carcinoma in situ

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Figure 5: Photomicrograph showing normal intervening breast tissue

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Discussion

PT is a rare fibroepithelial tumor. As per the 2019 World Health Organization classification, PT is subdivided into benign, borderline, and malignant subtypes. The current histological criteria for malignant PT are increased stromal cellularity, infiltrating margins, cellular atypia, stromal overgrowth, mitosis (>10/10 HPF), and necrosis. Heterologous differentiation of stromal cells categorizes the tumor as malignant phyllodes irrespective of the presence or absence of other histological criteria except for the well-differentiated liposarcoma element.^[1] Malignant PT has marked stromal overgrowth with a scanty epithelial component and increased mitoses or necrosis. The stromal component can be of the homologous type or shows heterologous elements such as chondrosarcoma, liposarcoma, osteosarcoma, angiosarcoma, or fibrosarcoma.

Rarely, carcinoma could originate within PT's epithelial cells or adjacent breast tissue.^[7] In this case, there was a collision tumor of two components such as malignant PT having heterologous chondrosarcomatous and osteosarcomatous differentiation, and invasive ductal carcinoma having DCIS. Both the tumors were discontinuous and at a distance of 3 cm from each other. Both macroscopic appearance and microscopic appearance of the intervening breast tissue were normal. All the sampled axillary lymph nodes were positive for carcinoma. Coexistence of such two histologic components in homolateral breast has been rarely published. Kefeli et al.^[6] reported a case of coexistence of homolateral invasive ductal carcinoma and malignant PT at the same time. They found malignant PT with chondrosarcomatous and liposarcomatous differentiation and also found metastatic carcinomatous deposit in axillary lymph node. Muthusamy and Mehta^[8] reported a case of malignant PT with distinct invasive carcinoma in the same breast as synchronous collision tumor in a 51-year-old female.

PT is treated by wide local excision or simple mastectomy. Mastectomy with axillary lymph node sampling becomes mandatory if associated with carcinoma.^[9],[10] In this case, on mammography, carcinomatous tumor was masked by a huge PT and the axillary lymph nodes were not appreciated on imaging as well as clinically. Preoperative diagnosis was PT, and simple mastectomy was performed. Due to enlarged lymph nodes at surgery, only level I axillary lymph nodes were sampled. Only sereal sectioning of the breast specimen detected another tumor at 3 cm far away from the PT. Hence, extensive sampling of the specimen plays a significant role in diagnosing these rare collision tumors of the breast. Since there is no consensus on surgical margin clearance for both borderline and malignant PTs, wide local excision or simple mastectomy with a tumor-free margin of ≥1 cm has been widely accepted.^[11] In the case of collision tumors of PT and breast carcinoma, treatment depends on the individual components. Therefore, TNM staging, immunohistochemistry tests for ER, PR, and Her-2 status and molecular tests become relevant for carcinoma breast.^[2]

Conclusion

PT rarely may be associated with carcinoma breast. Irrespective of the subtype of phyllodes, the tumor staging, prognosis, and treatment depends on the presence of concurrent carcinoma. Hence, careful specimen sampling is decisive to exclude collision tumors in the breast.

Declaration of patient consent

The authors certify that they have obtained all appropriate patient consent forms. In the form, the patient(s) has/have given his/her/their consent for his/her/their images and other clinical information to be reported in the journal. The patients understand that their names and initials will not be published and due efforts will be made to conceal their identity, but anonymity cannot be guaranteed.

Financial support and sponsorship

Nil.

Conflicts of interest

There are no conflicts of interest.

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