Invasive Micropapillary Carcinoma of the Breast


  • Breast carcinoma with a prominent (pseudo) micropapillary pattern

Diagnostic Criteria

  • Numerous small pseudo-papillary clusters of cells
    • No fibrovascular cores
    • Frequent central lumen formation in clusters
    • Peripherally located nuclei frequently bulge out with knobby appearance, "the hedgehog" tumor
  • Clusters surrounded by clear spaces
    • One or only a few clusters per space
    • Scant mucin rarely detectable in spaces
  • Spaces surrounded by loose fibrocollagenous stroma
  • Frequent high nuclear grade reported in some series
  • Frequently has abundant eosinophilic cytoplasm
  • Frequent lymphatic involvement
  • Occasional psammoma bodies
  • Associated DCIS may be of various types
  • Pattern may be predominant or focal
    • No clinical difference between predominant and focal cases
    • No reported cutoff for minimal significant amount of pattern
    • Report such cases as mixed
  • Frequently mixed with infiltrating ductal carcinoma
    • Rarely mixed with other type


  • Incidence
    • Pure about 1%
    • Mixed about 4-7%
  • Frequent local recurrence (70-90%)
  • Poor prognosis
    • Approximate 40% dead of disease in three years
    • Not independent of stage
      • Linked to high incidence of nodal involvement
  • Rare cases reported in males

Grading / Staging / Report

  • 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 formationScore
>75% tubules1
10-75% tubules2
<10 span="" tubules="">3

Nuclear pleomorphism (most anaplastic area)Score
Small, regular, uniform nuclei, uniform chromatin1
Moderate varibility in size and shape, vesicular, with visible nucleoli2
Marked variation, vesicular, often with multiple nucleoli3

Mitotic figure count per 10 40x fields (depends on area of field, see key below)Score
0.096 mm20.12 mm20.16 mm20.27 mm20.31 mm2
  • 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 componentsOverall grade
3-5 pointsGrade I (well differentiated)
6-7 pointsGrade II (moderately differentiated)
8-9 pointsGrade III (poorly differentiated)
  • Micropapillary carcinoma is associated with frequent lymph node metastases
    • Seen even with primary tumors <1 cm="" span="">
    • Seen even with mixed tumors with small micropapillary component
    • Nodal involvement is frequently by micrometastases
  • 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
  • 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
  • Regional lymph nodes
    • Report findings as described above

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