P63%20Expression%20in%20Breast%20Cancer

1
P63 Expression in Breast Cancer

• A Highly Sensitive and Specific Marker of
  Metaplastic Carcinoma
• Meryem M. Koker, MD and Celina G. Kleer, MD
• (Am J Surg Pathol 2004281506 1512)

2
Abstract

• p63, a member of the p53 gene family, is involved
  in cellular differentiation and is expressed in
  the nuclei of myoepithelial cells of normal
  breast.
• In this study, we determined p63 expression in a
  large number of breast carcinoma, including
  metaplastic carcinoma, and in Phyllodes tumors
  and sarcoma.

3

• 189 invasive breast carcinomas, including 15
  metaplastic carcinomas, as well as 10 Phyllodes
  tumors, and 5 pure sarcoma of the breast for
  pattern and intensity of p63 staining using an
  anti-p63 antibody (clone 4A4, Neomarkers)
• p63 is strongly expressed in 13 of 15 metaplastic
  carcinoma (86.7).
• p63 is positive in all the metaplastic carcinoma
  with spindle cell and/or squamous differentiation
  (12 od 12).

4

• Only 1 of 174 (0.6) nonmetaplastic invasive
  carcinomas was positive for p63.
• All Phyllodes tumors and sarcomas were
  consistently negative for p63 expression.
• The sensitivity and specificity of p63 as a
  diagnostic marker for metaplastic carcinoma was
  86.7 and 99.4
• p63 as part of the diagnostic workup of
  challenging spindle cell tumors of the breast as
  a highly specific marker for metaplastic
  carcinomas.

5
??

• Metaplastic carcinoma of the breast (MCB) are a
  rare and heterogeneous group of tumors defined by
  a cellular component with an appearance other
  then epithelial and glandular.
• These tumors may be biphasic and contain
  glandular elements mixed with a nonglandular
  component.
• The majority of metaplastic carcinoma exhibit
  spindle cell with or without squamous
  differentiation.

6

• The spindle cell component of metaplsic carcinoma
  from low-grade fibromatosis-like lesions to
  high grade spindle cell malignancies resembling
  fibrosarcoma or malignant fibrous histiocytoma.
• The diagnosis of metaplastic carcinoma is
  straightforward when a direct transition from
  glandular epithelial to metaplastic elements is
  evident, but it becomes a diagnostic challenge
  when the neoplasm is entirely composed of spindle
  cells.

7

• p63 is located on chromosome 3q27. Its gene
  product is crucial for maintenance of a stem cell
  population in several epithelial tissue and is
  necessary for the normal development of the
  epithelial organs including mammary glands.
• p63 is also expressed in the nuclei of
  myoepithelial cells of normal breast ducts and
  lobules.
• Recently, p63 and other myoepithelial cell
  markers have been described in matrix-producing
  and metaplastic carcinomas of the breast,
  suggesting that these tumors share a
  myoepithelial cell differentiation.

8

• Given the specificity of p63 for myoepithelial
  cells in the breast and the possible
  myoepithelial differentiation of spindle cell
  metaplastic carcinoma, we postulated that p63
  would be a good marker to distinguish spindle
  cell metaplastic carcinoma from other mesenchymal
  neoplasm.
• Characterize the expression of p63 in a large
  group of invasive carcinomas of different
  histologic types, sarcomas, and Phyllodes tumors
  of the breast define its diagnostic utility.

9
Materials and MethodsCase Selection, Pathologic
Evaluation and Immunohistochemistry

• A total of 201 breast tumors were identified by a
  retrospective search through the surgical
  pathology files at the University of Michigan,
  comprising 189 invasive carcinomas, including 15
  metaplastic carcinomas. Ten Phyllodes tumors and
  5 primary breast sarcomas were also retrieved.

10

• MCB , the architectural pattern and the presence
  of epithelial and or heterologous elements were
  noted.
• The MCB were graded on the basis of the
  sarcomatoid component as low-, intermediate-, or
  high-grade following described criteria.
• In all cases, the diagnosis of MCB was confirmed
  by positive cytokeratin staining including a
  cytokeratin cocktail (AE1/AE3, CAM5.2) and/or a
  high molecular weight cytokeratin stain (34ßE12)

11

• A subset of the nonmetaplastic invasive carcioma
  (160 cases) was arrayed in a high-density tissue
  microarray.
• At least three tissue core (0.6 mm diameter) were
  sampled from different areas of each tumor to
  account for tumor heterogeneity using an
  automated arrayer (Beecher Instruments).
• Immunohistochemistry using an anti-p63 polyclonal
  antibody was performed on the whole tissue
  sections and on the tissue microarray
  simultaneously using standard biotin-avidin
  complex technique.

12

• The p63 antibody (clone 4A4, NeoMarkers, Fremont,
  CA) was used at a 1100 dilution, incubated for
  15 mins with citrate buffer at pH 6, and
  subjected to microwave antigen-retrieval
  pretreatment.
• Normal myoepithelial cells around ducts and
  lobules served as positive internal controls.
• A tumor was considered positive when ?10 of the
  neoplastic cells unequivocally expressed p63 in
  the nuclei and negative when less than 10 of the
  malignant cells stained for p63.

13
Results

• Histopathologic features
• Of the 189 invasive carcinomas, 159 were ductal,
  10 were lobular, 5 had ductal and lobular
  features, and 15 were metaplastic.
• Of the metaplastic carcinomas, 12 tumors had
  spindle and/or squamous areas and 3 had cartilage
  (Fig 1)
• Table 1

14

• Fig 1 Histologic feature of metaplastic
  carcinoma.
• A, Biphasic metaplastic carcinoma with
  well-demarcated spindle and epithelial
  components.
• B, Metaplastic carcinoma with spindle and
  epitheloid cells

15

• Fig 1 C, biphasic metaplastic carcinoma with a
  squamous area that blends imperceptibly with the
  surrounding spindle cell elements. D,
  metaplastic carcinoma with spindle cells and
  dense collagenized stroma, referred to as
  keloidal type

16
(No Transcript)
17

• The low- and intermediate- grade spindle cell MCB
  were characterized by elongated, fusiform cells
  with minimal to moderate cytologic atypia and
  rare or no mitoses. In contrast, the high-grade
  spindle cell carcinomas displayed marked
  pleomorphism, hyperchromasia, and numerous
  atypical mitoses.
• The neoplastic cells in both low- and high- grade
  spindle cell carcinomas infiltrated adjacent
  mammary and adipose tissue and were interrupted
  by dense collagen bands.

18

• p63 Expression in Invasive Carcinomas of the
  Breast
• p63 was expressed in the nuclei of myoepithelial
  cells of normal ducts and lobules adjacent to the
  carcinomas, which also served as internal
  positive controls in all cases (Fig 2a)
• p63 was not detectably expressed in the luminal
  cells of normal structures in any cases. Stromal
  fibroblasts and myofibroblasts were consistently
  negative in all case.
• Tab 2, Fig 2

19

• Fig 2 A. p63 expression in normal breast and in
  metaplastic carcinomas. A, normal terminal-duct
  lobular unit with p63 expressing myoepithelial
  cells, which served as positive internal control.

20

• Fig 2 B-F, Strong and diffuse expression of p63
  in metaplastic carcinomas with spindle and
  squamous areas. Note that the staining is crisp
  and easily discernible even at low power.

21
(No Transcript)
22

• The single nonmetaplastic carcinoma that was
  positive for p63 was a high-grade invasive ductal
  carcinoma with no special features however, the
  percentage of positive malignant cells was much
  lower than in the metaplastic carcinoma (10 vs
  mean of 70)
• p63 was negative in all the other invasive
  ductal, lobular and mixed ductal and lobular
  carcinoma.

23

• p63 Expression in Mesenchymal tumors of the
  Breast
• p63 was consistently negative in the spindle and
  epithelial cell components of all benign and
  malignant Phyllodes tumors
• Fig 3
• The sensitivity and specificity of p63 as a
  marker for metaplastic carcinoma is 86.7 and
  99.4, respectively, with a 100 specificity for
  MCB with spindle cell and/or squamous areas.

24

• Fig 3 A and B P63 is not expressed in Phyllodes
  tumors and sarcomas of the breast. A and B.
  Phyllodes tumor

25

• Fig 3.C and D Note that p63 is only expressed in
  the normal myoepithelial cells associated with
  the epithelial component. The spindle cells are
  negative. C and D, Primary osteosarcoma of the
  breast, negative for p63

26
Discussion

• Traditional, MCB has been defined as a malignant
  tumor in which part of all of the carcinomatous
  epithelium is transformed into a nonglandular
  (metaplastic) growth process.
• The most common metaplastic components are
  spindle cell and squamous, wereas heterologous
  elements including osseous, chondroid, and other
  sarcomas comprise a minority of tumors.
• MCB with a prominent spindle cell component
  display histologic patterns ranging from those
  resembling highly pleomorphic and anaplastic
  sarcomas to bland benign-appearing lesions.

27

• To data, the best mechanism other than
  morphologic examination for differentiating MCB
  from these other spindle cell tumors has been
  cytokeratin staining.
• Several studies hae shown that staining with a
  broad-spectrum anti-CK antibody or high molecular
  weight CK (34ßE12) provides the most sensitive
  marker for MCB.
• Other markers, such as smooth muscle actin, CK5,
  CK14, CAM5.2, and AE1/AE3, have also been
  examined for their utility in the diagnosis of
  MCB, but more than half of the cases were
  negative for any one of these antibodies.

28

• Importantly, CK-positive metaplastic carcinomas,
  even those stained with 34ßE12 or broad-spectrum
  CKs, often only show focal or patchy positive,
  particular in small core biopsies, leading to
  potential misdiagnoses.
• Apart from the CK stains, CD34, smooth muscle
  actin, vimentin, and occasionally Bcl-2 have been
  proposed as helpful adjuncts when the
  differential diagnosis includes MCB, sarcoma of
  the breast, and Phyllodes tumor.

29

• However, borderline and malignant Phyllodes
  tumors, the types most likely to cause diagnostic
  confusion with metaplastic carcinomas, are much
  less likely to be positive for any of these
  markers.
• All the MCB with spindle cell and squamous
  components stained strongly for p63 in the
  nuclei, which confirms previous reports.
• Surprisingly, we found that only 1 of the 174
  nonmetaplastic invasive carcinoma (0.6) was
  positive for p63 expression, and the percentage
  of positive cells in this carcinoma was much
  smaller then in the MCB (10 vs. a mean of 70
  for MCB)

30

• This tumor was an invasive ductal carcinoma, with
  high histologic grade and no special features.
• While all the of metaplastic spindle cell
  carcinomas stained strongly with p63, none of the
  Phyllodes tumors or primary breast sarcomas
  showed any p63 expressed.
• Emerging data suggest that the metaplastic
  component and the adenocarcinoma have a clonal
  origin.

31

• It has been suggested that these tumors arise
  from a single stem cell, a group of different
  cells, or a common progenitor cell capable of
  differentiating into other cell types.
• Using laser capture microdissection of a tumor
  with carcinomatous and sarcomatoid component,
  Wada et al found that both areas had identical
  patterns of X-chromosome inactivation and the
  same of p53 mutation, strongly supporting the
  hypothesis that this tumor is derived from a
  single totipotent stem cell.

32

• Furthermore, the concept that the metaplastic
  spindle elements have myoepithelial
  differentiation is supported by the present study
  and by several studies showing that these cells
  are reactive for myoepithelial markers, including
  high molecular weight CK, p63, and maspin.
• In summary, p63 is a specific and sensitive
  marker for MCB, and particularly specific for
  metaplastic carcinomas with spindle and/or
  squamous areas

33

• It is a highly complementary stain to CK because
  p63 is a nuclear marker, which has a strong and
  diffuse staining pattern that is easily
  discernible, even at low power.
• We propose the inclusion of p63 in the diagnostic
  workup of challenging spindle cell tumors of the
  breast.

34
(No Transcript)
35
(No Transcript)
36
(No Transcript)