Rosen's Breast Pathology, 4e

360

Chapter 11

FIG. 11.36.  DCIS, spindle cell. A: The carcinoma cells have spindle-shaped nuclei with traces of palisading. B: Rosette-like microlumens are present. C: Spindle cell carcinoma with a central fibro- vascular stromal core. This focus was part of a complex solid papillary carcinoma with an extensive spindle cell component. D: Spindle cell DCIS with palisading epithelial cells.

microinvasion when DCIS inhabits SA (Fig. 11.42). In a study of 24 cases of DCIS involving SA, Moritani et al. 140 found that most DCIS that only involved SA were “non-high-grade,” whereas DCIS not confined to SA was more often high grade. Nerves may be incorporated in SA when no carcinoma is present. 141 The presence of this phenomenon when there is DCIS in the adenosis is not indicative of invasion. Neu- ral entrapment has also been observed in areas of sclerosing papillary DCIS not associated with SA. 142 DCIS has been found to arise near and in radial scleros- ing lesions , so-called radial scars (Figs. 11.43 and 11.44). The presence of an underlying radial sclerosing lesion (RSL) is indicated by the overall configuration of the lesion and the presence of benign proliferative foci such as duct hyperpla- sia, cysts, SA, and apocrine metaplasia. DCIS with a stellate growth pattern can present as a RSL(Fig. 11.45). Incomplete samples of radical scar lesions obtained in needle core biopsy specimens are difficult to assess for DCIS or for invasion, and they are likely to be reported as atypical duct hyperplasia. A diagnosis of radial scar without atypical changes based on a partially sampled lesion on a needle core biopsy does

not preclude the finding of carcinoma in the subsequent excision. In a study of 49 cases of radial scar (all without associated atypical epithelial proliferation) that had been di- agnosed on needle core biopsy, Bianchi et al. 143 found three cases of DCIS (and one of invasive lobular carcinoma) in the subsequently performed excisional biopsy. However, Reset- kova et al. 144 reported no instances of “upgrade” to invasive or in situ carcinoma in a study of 19 radial scars diagnosed on needle core biopsy that underwent subsequent excision of the lesion. Another 61 patients with a diagnosis of radial scar on needle core biopsy were followed clinically and ra- diologically without apparent progression of disease. The authors concluded that ample sampling with larger (11G or 9G) needles and radiologic correlation could obviate the need for excision in radial scars diagnosed on needle core biopsy. 144 Concurrent intraductal and in situ lobular carcinomas are present when there are separate foci of carcinoma with these histologic features in the breast. This is illustrated by instances in which the lobular lesion with the classical small cell phenotype of lobular carcinoma is limited to TDLUs