Page 546 - Concise Pathology for Exam Preparation ( PDFDrive )

19 The Breast 531

(b) Medullary carcinoma
(i) Though germline BRCA1 mutations are not present in most of these, hyper-
methylation of the BRCA1 promoter leading to downregulation of BRCA1
expression is noted in 67% tumours.
(ii) They presents as well-circumscribed, soft, fleshy masses (medulla in Latin
means marrow), which may be confused with benign lesions.
(iii) Histopathology shows:
- A solid syncytial arrangement occupying more than 75% of the tumour,
with the tumour cells being large, pleomorphic, having vesicular nuclei
with prominent nucleoli with frequent mitoses
- Lymphoplasmacytic infiltrate surrounding and within the tumour nests
- Pushing and noninfiltrative tumour margins
- Minimal or absent DCIS
- Absence of lymphatic or vascular invasion. Lymph node involvement
is rare.
- A better prognosis than NST.
The current WHO classification recommends medullary carcinomas and carcino-
mas with similar features into a group termed ‘carcinomas with medullary fea-
tures’.
(c) Mucinous (colloid) carcinoma
(i) Commonly presents as a circumscribed mass in older women and progresses
slowly
(ii) Soft in consistency with a pale grey-blue gelatinous appearance (due to
mucin)
(iii) Histopathology shows large pools of mucin, scattered within which are small
clusters of malignant cells.
(d) Tubular carcinoma
(i) Incidence of this tumour has increased after initiation of mammographic
screening.
(ii) Affects women in their late forties.
(iii) Tumours are frequently multifocal and bilateral.
(iv) Histopathology shows well-formed tubules lined by malignant cells. There is
absence of myoepithelial cells. Tubular pattern should be seen in more than
75% of the tumour.
(v) Apocrine snouts are present and calcification is common.
(vi) Axillary metastasis is seen in fewer than 10% of the cases (excellent prognosis).
(e) Invasive papillary carcinomas
(i) A rare invasive carcinoma with papillary architecture.
(ii) Clinical presentation is similar to NST but prognosis is better.
(f ) Metaplastic carcinoma
(i) Represents a group of invasive breast cancers showing differentiation of the
tumour cells into squamous and mesenchymal elements (spindle, chondroid,
osseous and rhabdomyoid cells) which are mixed with carcinoma of usual
type.
(ii) Based on nuclear features, metaplastic carcinomas are classified into
‘low-grade tumours’ (eg, low-grade adenosquamous carcinoma or low-grade
spindle cell carcinoma), or ‘high-grade tumours’ (eg, high-grade squamous
cell carcinoma, or high-grade spindle cell carcinoma).
(iii) They are triple-negative tumours, but have a worse prognosis than other forms
of triple-negative breast cancers.

Prognostic or Predictive Factors of Carcinoma Breast
Major prognostic factors
• Lymph node metastases: Axillary lymph node status is the single most important
prognostic factor. With no involvement, 10-year disease-free survival rate is 70–80%,
with 1–3 positive nodes; it is 35–40%, with more than 10 positive nodes, it is 10–15%.

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