Unusual collision tumor with infiltrating ductal carcinoma and breast skin squamous cell carcinoma: A case report and literature review

Abstract

Introduction: Breast cancer is the most common diagnosed cancer among women worldwide. Invasive ductal carcinoma (IDC) is the most common type, on the other hand, squamous cell carcinoma of the skin (SCC) overlying the breast is a rare tumor. The co-presence of two tumor types in one organ is even a rarer entity, termed as collision tumor. Only 3 known cases of collision tumor with breast invasive ductal and skin squamous carcinoma were reported in the literature.

Case presentation: An otherwise medically free 91-year-old, postmenopausal, female presented with left breast fungating mass for four months. Pre-operative core tissue biopsy and incisional skin biopsy revealed two distinct tumor subtypes of invasive ductal carcinoma, positive for progesterone, estrogen receptors and negative for human epidermal growth factor receptor 2, as well as skin squamous cell carcinoma, and axillary lymph node metastasis. Patient underwent left breast modified radical mastectomy and split skin grafting for wound closure. The final histopathology was consistent with grade 2 IDC. The nipple and areola complex were involved by moderately differentiated squamous cell carcinoma. Currently patient on adjuvant hormonal treatment. Follow up showed no local recurrence or distal metastasis.

Conclusion: Collision tumors of the breast with IDC and SCC of the overlying skin is very rare. The surgeon has to be aware of of such entity as the proper peri-operative management should be tailored to target the most aggressive histologic subtype.

Keywords: Breast; Cancer; Case report; Collision; Invasice ductal cancer; Squamous cell cancer.

Fig. 1

Left breast fungating ulcerating mass 12 × 7 include nipple areolar complex not attached to chest wall, no axillary lymphadenopathy.

Fig. 2

Ultrasound of the left breast shows large heterogeneous lesion with increased peripheral vascularity at the retroareolar region reaching skin keeping with ulcerative mass; measures 3.6 × 3 × 3.5 cm. Associated with skin thickening.

Fig. 3

Mammogram shows left retroareolar region 6.6 × 5.5 cm irregular, dense mass associated with faintly seen microcalcifications.

Fig. 4

Computed tomography of chest, abdomen and pelvis revealed Left retro-areolar mass invading the skin with suspicious left axillary lymph nodes.

Fig. 5

showing grade 2 invasive ductal carcinoma, and irregular islands of invasive well differentiated squamous cell carcinoma in different cores (H&E).

Fig. 6

Core showing nests of squamous cell carcinoma infiltrating deeply in the dermis. (a) original magnification 10X (b) Higher magnification of squamous cell carcinoma component infiltrating the dermis with surrounding desmoplastic reaction. (H&E, original magnification 40X).

Fig. 7

showing (a) CK5/6 featuring positive strong diffuse staining in squamous cell carcinoma and completely negative staining in invasive ductal carcinoma. (b) showing p63 which highlights the basal layer of squamous cell carcinoma and it is negative in the invasive ductal carcinoma.

Fig. 8

Core showing infiltrating ductal carcinoma. (a) H&E, original magnification 20X, (b) Higher magnification 40X.

Fig. 9

showing (a) ER stain: strong diffuse positivity in the invasive ductal carcinoma. (b) PR stain: strong diffuse positivity in invasive ductal carcinoma. (c) HER2: 2+ Negative result.