Squamous cell carcinoma of the breast (a case report).
Incidence of squamous differentiation in breast tumours is very low. Rare still is the squamous cell carcinoma of the mamma. Haagensen came across only 20 cases of squamous metaplasia in 50 years but there was no case of squamous cell carcinoma. The rarity of the lesion prompted us to report 6 cases in the last 7 years.
Six cases of squamous cell carcinoma of the breast could be detected during the last
7 years out of a total of 298 malignant tumours of the breast. The details of each case are shown in [Table 1]. All patients were females and their ages varies from 26 to 58 years; 5 of these were above the age of 40 years.
All patients presented with a painless lump in the breast. The duration varied from 2 to 12 months. In most of the cases, the upper and the outer quadrants of the right breast were involved. The lumps were not adherent to the deeper structures or skin in all the cases. The skin was not ulcerated. Axillary lymphadenopathy was seen only in two cases.
All the tumours were well circumscribed, larger than 4 cm, and creamish or yellowish in colour. In five out of six cases, these tumours showed single or multiple cystic cavities. Necrotic areas were seen in three cases.
All these tumours revealed sheets of large, polygonal squamoid cells with intercellular bridges and keratin formation. They were differentiated from squamous metaplasia by malignant nuclear criteria, and from medullary cells and apocrine cells by special stain for keratin. The tumours from cases 1, 5, and 6 showed sheets and masses of malignant squamous cells, separated by fibrous connective tissue stroma. There was no evidence of any other cellular pattern. Therefore, these three cases were diagnosed as having pure squamous cell carcinoma of the breast.
Case 3 and 4 revealed large areas of elongated spindle shaped cells, with hyper-chromatic nucleus and pink cytoplasm aljacent to the masses of squamoid cells. In case 2, a part of the tumour was composed of round to oval cells, with large hyperchromatic nucleus and scanty cytoplasm. The cells were arranged in groups, and at places, revealed ductular pattern. The malignant squamous cells were seen in the vicinity of the necrotic area.
Cysts were present in five out of six cases. [Fig. 1] They were containing necrotic material. The lining of the cyst was seen in one case only, and it was apocrine epithelial in nature. In all the three cases of axillary lymphadenopathy, metastasis of squamous cell carcinoma was seen.
Squamous cell carcinoma of the breast falls into four categories (Azzopardi et al):
(1) Adenocarcinoma, showing varying degrees of squamous differentiation,
(2) Squamous cell carcinoma, with extensive spindle cell metaplasia mimicking fibrosarcoma and carcinosarcoma,
(3) Squamous cell carcinoma, arising in cystosarcoma phylloides, and
(4) Pure squamous cell carcinoma without spindle cell metaplasia.
In the present series, cases 1, 5 and 6 were pure squamous cell carcinomas, case 2 was that of adenocarcinoma with squamous differentiation and cases 3 and 4 were of squamous cell carcinoma with spindle cell element, mimicking fibrosarcoma. Keratin staining was positive in all the cases.
If one excludes the tumours of the nipple region and of the skin and its appendages, pure squamous cell carcinomas if the mamma is rare, the reported incidence being 0.5% to 2%. In the present series, the incidence is 2.01%. Appendage tumours, especially of the hair sheath can mimic squamous cell carcinoma very closely, as they are situated deep to the epidermis and can be confused with the tumours of the breast. Medullary carcinoma and apocrine metaplasia are sometimes mistaken for squamous cell carcinoma because of the large cell size and eosinophilia of the cytoplasm.
Cornog et al defined the criteria to identify squamous differentiation in various tumours; these are the presence of (1) intercellular bridges and (2) evidence of keratin formation in polygonal squamoid cells. These authors were able to detect squamoid metaplasia far more frequently and have reported a series of twenty four cases. There were only 2 cases of squamous cell carcinoma in this series and even these were found to be continuous with the skin. Hence, the possibility of the tumour arising from the mammary skin could not be excluded. Fisher et al insisted on seeing formation as well as pavementing, in addition to intercellular bridges and glycogen in the cells to classify the tumour as a squamous cell carcinoma.
We have classified the cases according to the classification suggested by Azzopardi et al. In our series, Case 2 revealed areas of adenocarcinoma on taking multiple sections. Cases 3 and 4 showed transformation of squamoid cells into spindle shaped cells. The neoplasm had a sarcomatoid appearance in this area. Cases 1, 5 and 6 showed only squamoid cells; no other elements could be detected even after studying multiple sections. In these cases, keratin stain was strongly positive. Hence, these three cases were classified as pure squamous cell carcinoma. None of these tumours was arising in cystosarcoma phylloides. In our tumours, squamous differentiation is a constant feature which is supported by lymph node metastasis with squamous element. The appearance of squamous foci in metastasis and the presence of malignant cytologic characters emphasize the malignant character of the neoplasm.
Squamous cell carcinoma of the breast is the tumour of elderly age group. In our study, majority of cases were beyond the age of forty years. However, one case which showed squamous cell carcinoma with adenocarcinoma was only 26 year old. The average age in Haagensen's series was 50 years. The presenting symptom in all the cases was a painless lump in the breast. The duration varied, from 2 months to one year. All the tumours were larger than 5 cm. Cystic cavities (single or multiple) were seen in five out of six cases. Other workers,, have also described such lesions. Salm has described massive epidermoid metaplasia with keratin cyst formation even in a giant fibroadenoma of the breast. We did not find any keratinous cysts.
Behaviour of patients with squamous cell carcinoma is thought to be worse than those with other carcinomas. Haagensen et al however did not find the prognosis of his patients to be worse than the others. This would, to a large extent, be governed by the amount of squamous differentiation one sees in a given tumour. Small foci of squamous cells, widely scattered, would have a different significance from a substantial squamous differentiation which is very extensive and a dominant feature. In three of our cases, the squamous differentiation was extensive. Follow-up data, however is not available with us.