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Special types of carcinoma



20% of breast carcinomas are of special type and the majority of these are lobular carcinomas. Tubular and mucinous carcinomas occur next most frequently and thereafter the remaining special types are seen infrequently. In order to make a diagnosis of a special type of carcinoma >90% of the tumour is required to show the particular pattern in question. Special types of carcinoma should be distinguished from mixed carcinomas where the special type areas occupy between 50 and 90% of the tumour area with the remaining area being usually of no special type.

See also
Common Cancers


It is recommended that special types of carcinoma are graded using the same criteria as no specicial type cancers.

See also Grading Breast Cancer

See also Prognosis

Invasive carcinomas of special type:





Invasive lobular carcinoma


These tumours, in their classical form, are characterised by a single file infiltrating pattern. Tumour cells are normally intermediate in size and a common finding is the presence of a squared off clear space between adjacent tumour cells. Cytoplasmic vacuolation is common and another frequently encountered feature is the presence of a rather granular eosinophilic cytoplasm. A number of variant forms are recognised (see link below).




Invasive lobular carcinoma - classical pattern
Typical streaming pattern of classical invasive lobular carcinoma Single file runs of tumour cells with squared-off edges. Note apparent clear space at cell-cell interface
Small runs of invasive lobular carcinoma (arrows) with two adjacent foci of LCIS


E Cadherin and beta catenin immunohistochemistry:




Invasive lobular carcinoma showing aberrant E Cadherin staining and cytoplasmic 'Golgi' pattern beta catenin staining - note the normal pattern of beta catenin staining in the duct on the left.
pleomorphic lobular carcinoma aberrant e cadherin staining in lobular carcinoma
cytoplasmic 'Golgi' pattern beta catenin staining in lobular carcinoma


Classical lobular carcinoma showing absent/near-absent E Cadherin staining
classical lobular carcinoma - H&E  e cadherin staining in classical lobular carcinoma


Invasive Tubular Carcinoma


Clinical basics:


  • 2% of all invasive cancers
  • Frequently impalpable
  • More common in screening population
  • Usually detected as small stellate leions on mammograms
  • When identified, review of previous mammograms may reveal the lesion, and show how slow growing it can be
  • A small percentage of cases, probably < 2% will have axillary node metastases, often subtle
  • Excellent prognosis

Histological diagnosis:




Tubular carcinoma - the scale bar (lower right) is 1mm. Pass the mouse over this image for a high power view (arrows point to calcs).
Tubular carcinoma

Tubular carcinoma - low power High power view of invasive tubular carcinoma showing single layer of infiltrating tumour cells with striking luminal cytoplasmic apical snouts

Tubular carcinoma of breast (Example 2)
Tubular carcinoma - low power High power view of invasive tubular carcinoma showing single layer of infiltrating tumour cells with striking luminal cytoplasmic apical snouts
Low power view of an invasive tubular carcinoma. More than 90% of the tumour shows tubular differentiation Medium power view of invasive tubular carcinoma


Invasive mucinous carcinoma





Mucinous carcinoma of breast

See also Mucocele-like lesion



Invasive Cribriform Carcinoma





Cribriform carcinoma of breast
Low power view Infiltrating edge of tumour (top left) and part of single duct showing cribrigorm intermediate grade DCIS (lower right)
Medium power view of invasive cribriform carcinoma High power view of invasive cribriform carcinoma
Focus of perineural invasion Metastatic tumour in a nodal capsular lymphatic


Low power view (x 10) of invasive cribriform carcinoma (example 2).
Arrow points to luminal calc.

Low power view of invasive cribriform carcinoma


High power view (x 40) of cribriform carcinoma (example 2).
Note predominance of grade 1 nuclei -See also
Grading Breast Cancer

High power view of invasive cribriform carcinoma


Invasive Medullary-like Carcinoma





Medullary-like Carcinoma - The tumour is very uncommon. It has a pushing margin, a heavy lymphocytic infiltrate, grade 3 features and 'syncitial' morphology (cell boundaries difficult to distinuish). They commonly display a basal phenotype - note positive CK5/6 immunostain below.
Pushing interface between medullary carcinoma and adjacent stroma - low power Heavy lymphocytic infiltration of tumour stroma
Syncitial appearance of tumour cells with high grade features CK5/6 positive immunostain supporting a basal phenotype

Other Invasive Carcinomas



These include: