Case 12 Clinical history Female aged 54 years. She presented with a palpable lump in the right breast. This was clinically malignant and FNAC revealed malignant cells. A wide local excision and axillary dissection were carried out. Histological appearances - A-E The section shows an invasive carcinoma with a curious architectural pattern - clusters of tumour cells surrounded by clear peripheral spaces (A,B). Glandular differentiation is seen only focally (T3), there is marked nuclear pleomorphism (P3) (C) and intermediate numbers of mitoses (M2) - grade is therefore assigned as 3. Possible explanations for architectural pattern Vascular invasion Fixation artefact Special tumour type The pattern is not due to vascular invasion (VI) - vascular markers are negative (eg, CD34 (D)), although VI is present at the tumour periphery in other blocks. The tumour is well fixed and little true shrinkage artefact is seen. Immunostaining for epithelial mucin antigen (EMA) shows that the tumour cells have a reverse polarity (E). This type was first described by Peterse 1 as a tumour with an inside-out pattern, but subsequent authors have applied the term invasive micropapillary carcinoma. 2-4 They tend to be of high histological grade and frequently exhibit vascular invasion and lymph node metastases. 2-4 Most series demonstrate poor long-term survival. Diagnosis Invasive micropapillary carcinoma, grade 3 Learning points · Tumours with distinctive architecture can, and should, be assigned to special subtypes, especially if this provides prognostic information. References 1 Peterse JL. Breast carcinomas with an unexpected inside out growth pattern. Rotation of polarisation associated with angioinvasion. Pathol Res Pract 1993; 189: 780. 2 Siriaungkul S, Tavassoli FA. Invasive micropapillary carcinoma of the breast. Mod Pathol 1993; 6: 660-662. 3 Luna More S, Gonzalez B, Acedo C et al. Invasive micropapillary carcinoma of the breast. A new special type of invasive mammary carcinoma. Pathol Res Pract 1994; 190: 668-674. 4 Middleton LP, Tressera F, Sobel ME et al. Infiltrating micropapillary carcinoma of the breast. Mod Pathol 1999; 12: 499-504. |
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