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Zorluk: ZorPathology and Biopsy Interpretation

A 52-year-old woman is evaluated in the clinic following an abnormal screening mammogram that revealed a new, 1.5-cm cluster of pleomorphic microcalcifications in the upper outer quadrant of her right breast. She has no palpable breast masses, skin changes, or axillary lymphadenopathy on physical examination. A stereotactic core needle biopsy is performed.

Histopathologic evaluation of the biopsy specimens demonstrates markedly expanded terminal duct lobular units filled with a solid proliferation of atypical, monomorphic epithelial cells displaying high-grade nuclear atypia. The central portions of these involved spaces show extensive cellular necrosis accompanied by dystrophic calcifications. Immunohistochemical staining for p63 and smooth muscle myosin heavy chain (SMMHC) demonstrates a continuous, intact layer of cells surrounding the periphery of all the involved spaces.

Based on the histopathologic and immunohistochemical findings, which of the following is the most accurate diagnosis?

  1. Ductal carcinoma in situ, high gradeCevap
  2. B
    Invasive ductal carcinoma
  3. C
    Atypical ductal hyperplasia
  4. D
    Invasive lobular carcinoma
  5. E
    Sclerosing adenosis with microcalcifications

Cevap

Ductal carcinoma in situ, high grade
The correct diagnosis is high-grade ductal carcinoma in situ (DCIS). DCIS is a neoplastic proliferation of epithelial cells confined to the mammary ductal-lobular system. The critical distinguishing feature of an in situ lesion is the preservation of the surrounding myoepithelial cell layer and basement membrane, which demonstrates that the malignant cells have not invaded the surrounding breast stroma. Immunohistochemically, p63 (a nuclear marker) and smooth muscle myosin heavy chain (SMMHC, a cytoplasmic marker) are highly specific and sensitive for identifying myoepithelial cells. The continuous, intact staining of these markers in this biopsy definitively confirms the presence of an intact myoepithelial layer. Therefore, despite the alarming presence of high-grade nuclear atypia and comedonecrosis (central necrosis with dystrophic calcifications), the lesion is entirely in situ.

Adım Adım Çözüm

1
Analyze the clinical presentation and mammogram findings
A 52-year-old woman presents with a new cluster of pleomorphic microcalcifications on mammography, a finding highly suspicious for malignancy.
To establish the pre-test probability and context for interpreting the core needle biopsy.
2
Interpret the cellular features from the histopathologic description
The biopsy shows a solid proliferation of monomorphic epithelial cells with high-grade nuclear atypia and extensive central necrosis (comedonecrosis).
To determine the neoplastic nature and grade of the cellular proliferation.
3
Evaluate the immunohistochemical (IHC) stain results
Stains for p63 and SMMHC show a continuous, intact layer of cells surrounding the involved ductal-lobular spaces.
To determine if the lesion is in situ (intact myoepithelial layer) or invasive (absent or fragmented myoepithelial layer).
4
Synthesize findings to formulate a definitive diagnosis
High-grade malignant cells confined entirely within the ductal-lobular system by an intact myoepithelial layer indicates a high-grade in situ lesion.
To distinguish between invasive and in situ carcinoma, a distinction that fundamentally alters patient management and prognosis.

Anahtar Kavram

Distinguishing in situ from invasive breast carcinoma using myoepithelial immunohistochemical markers (p63, SMMHC).
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Pathology and Biopsy Interpretation

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