33 Special Types of Invasive Breast Carcinoma: Diagnostic Criteria ...

pleomorphic infiltrating lobular carcinoma compared to those with classical
infiltrating lobular carcinoma, this difference was not statistically significant.
Invasive lobular carcinoma, like InvDC,NST, can be treated conservatively with
partial mastectomy or only lumpectomy followed by whole breast irradiation (22).
Recurrence rates appear to be no higher than with InvDC,NST treated in the same
manner (61).
Clinicopathologic features: When using the criteria of Foote and Stewart, invasive
lobular carcinoma constitutes ~5% of the invasive carcinomas in most series (23-25),
but with less restrictive diagnostic criteria, the disease frequency increases up to ~14%
of invasive carcinomas (5,6,14,15). Invasive lobular carcinoma occurs throughout the
age range of most breast carcinomas in adult women (28 to 86 years, median age 45 to
56 years)(6,9,24-26,27,28). It appears more common in women over 75 years (~11%)
than in women under 35 years (29). Some data suggest that invasive lobular
carcinoma is more frequently bilateral than other invasive breast carcinomas (1-21).
Tumor size ranges from occult, focal lesions of microscopic dimension to tumors that
diffusely involve the entire breast. The median and average sizes of measurable
tumors are not significantly different from the dimensions of invasive duct carcinomas.
The gross presentation of infiltrating lobular carcinoma can be firm, like
InvDC,NST; but frequently, it may be difficult to detect when it fails to form a
discrete mass. In these cases, lesions of infiltrating lobular carcinoma can be difficult
to visualize mammographically. They may feel doughy when palpated and may
closely mimic benign breast disease (22). This gross presentation, coupled with its
often bland cytologic features, makes the frozen-section diagnosis and evaluation of
resection margins of infiltrating lobular carcinoma very treacherous. Recognition on
fine needle aspiration samples may also be difficult. The diagnosis of invasive lobular
carcinoma may be suspected in a fine-needle aspirate (30). FNA samples are usually
sparsely cellular, containing small cells with scanty, inconspicuous cytoplasm dispersed
singly or in small groups on the slide. Signet-ring cells may be found and linear
arrays of tumor cells are helpful characteristic features. Invasive lobular carcinomas
are not prone to form calcifications, but calcifications may be present coincidentally in
adjacent benign proliferative lesions. The detection of these tumors by mammography
depends largely on the recognition of a mass, but the latter does not have a specific or
characteristic mammographic appearance.
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