Some but not all features required for diagnosis of DCIS with discrete areas of rupture resulting in mucin pools in stroma, no groups of cells floating in mucin
Pools of mucin in stroma variably lined by bland epithelium, usually no groups of cells floating in mucin (if present they are normal ductal cells and are not complex), almost always a microscopic lesion
Mucinous carcinomas are characterized by cells floating in pools of mucin
Signet ring carcinomas are characterized by cells with intracellular mucin that indents the nucleus
Signet ring cells can be found in otherwise mucinous carcinomas
If at least 20% of cells are signet ring, designate as signet ring carcinoma
Prognosis is that of usual infiltrating carcinoma of identical grade
Signet ring carcinoma is usually a variant pattern of lobular carcinoma
If <20% of cells are signet ring, designate as mucinous carcinoma with signet ring cells
Prognosis may not be worse than pure mucinous carcinoma
Clinical
Ten year survival approximately 85%
Lymph node metastases are rare from pure low grade mucinous carcinoma, almost never if under 2 cm diameter
Lymph node metastases reported in 15-20% of cases, but many of these may be mixed mucinous/ductal cases
If metastases are present, review primary for evidence of another pattern
Grading / Staging / Report
Grading
Usually low grade cytology but all degrees of atypia may be found
Bloom-Scarff-Richardson grading scheme is most widely used
Total score and each of the three components should be reported
Based on invasive area only
Tubule formation
Score
>75% tubules
1
10-75% tubules
2
<10% tubules
3
Nuclear pleomorphism (most anaplastic area)
Score
Small, regular, uniform nuclei, uniform chromatin
1
Moderate varibility in size and shape, vesicular, with visible nucleoli
2
Marked variation, vesicular, often with multiple nucleoli
3
Mitotic figure count per 10 40x fields (depends on area of field, see key below)
Score
0.096 mm2
0.12 mm2
0.16 mm2
0.27 mm2
0.31 mm2
0-3
0-4
0-5
0-9
0-11
1
4-7
5-8
6-10
10-19
12-22
2
>7
>8
>10
>19
>22
3
Olympus BX50, BX40 or BH2 or AO or Nikon with 15x eyepiece: 0.096 mm2
AO with 10x eyepiece: 0.12 mm2
Nikon or Olympus with 10x eyepiece: 0.16 mm2
Leitz Ortholux: 0.27 mm2
Leitz Diaplan: 0.31 mm2
Mitotic count figures based on original data presented for Leitz Ortholux by Elston and Ellis 1991, with modifications based on pubished and measured areas of view
Evaluate regions of most active growth, usually in cellular areas at periphery
We employ strict criteria for identification of mitotic figures
Sum of above three components
Overall grade
3-5 points
Grade I (well differentiated)
6-7 points
Grade II (moderately differentiated)
8-9 points
Grade III (poorly differentiated)
Staging
TNM staging is the most widely used scheme for breast carcinomas but is not universally employed
Critical staging criteria for regional lymph nodes
Isolated tumor cell clusters
Usually identified by immunohistochemistry
Term also applies if cells identified by close examination of H&E stain
No cluster may be greater than 0.2 mm
Multiple such clusters may be present in the same or other nodes
Micrometastasis
Greater than 0.2 mm, none greater than 2.0 mm
Metastasis
At least one carcinoma focus over 2.0 mm
If one node qualifies as >2.0 mm, count all other nodes even with smaller foci as involved
Critical numbers of involved nodes: 1-3, 4-9 and 10 and over
Note extranodal extension
Report
In the context of mucinous carcinoma, the presence of mucin in a margin constitutes involvement by carcinoma
Excisions: the following are important elements that must be addressed in the report for infiltrative breast carcinomas
Grade
Total score and individual components
Size of neoplasm
Give 3 dimensions or greatest dimension
Critical cutoffs occur at 0.5 cm and at 2 cm
Margins of resection
Measure and report the actual distance of both invasive and in situ carcinoma
Angiolymphatic invasion
Indicate if confined to tumor mass, outside tumor mass or in dermis
(Extensive DCIS is not currently felt to be a significant predictor of behavior)
Results of special studies performed for diagnosis
Results of prognostic special studies performed
ER, PR, Proliferation marker, Her2neu
If studies were performed on a prior specimen, refer to that report and give results
Needle or core biopsies
Provisional grade may be given but may defer to excision for definitive grade
Presence of absence of angiolymphatic invasion
Results of special studies performed for diagnosis
Results of prognostic special studies if performed
ER, PR, Proliferation marker, Her2neu
State if studies are deferred for a later excision specimen
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