Case 3D -

Solid Papillary (Endocrine) Ductal Carcinoma in Situ

History: This specimen is from a 78 year old woman with unilateral nipple discharge. An open biopsy was performed. What is your diagnosis? Case 3D - Figure 1 Case 3D - Figure 2 Diagnosis: Solid Papillary (Endocrine) Ductal Carcinoma in Situ. Discussion: Maluf et al. and Tsang et al. have recently published series of cases referred to as solid papillary ductal carcinoma in situ by the former, and endocrine ductal carcinoma in situ, by the latter. Both authors emphasize the consistent expression of neuroendocrine markers (such as chromogranin) in these lesions. In the recent series by Maluf et al. and Tsang et al., at least half of the cases were accompanied by invasive carcinoma; three-fourths of these had mucinous (colloid) differentiation. In situ carcinomas with neuroendocrine features were initially described by Cross et al. in 1985. Histogenetically , the solid papillary/endocrine variant of in situ carcinoma is thought to be a precursor to the set of mucinous carcinomas, described by Scopsi et al., that are characterized by neuroendocrine differentiation. The importance of recognizing solid papillary/endocrine DCIS reflects the fact that it is has a confusing appearance that overlaps with benign papilloma or florid hyperplasia, especially when not accompanied by invasive carcinoma. Differential Diagnosis of Solid Papillary Carcinoma florid ductal hyperplasia papilloma LCIS solid variant of adenoid cystic carcinoma metastatic carcinoid tumor At low magnification, solid papillary/endocrine DCIS is comprised of a cluster of distended ducts filled with an expansile epithelial proliferation and surrounded by a relatively dense collagenous stroma. At low magnification, the epithelial proliferation has a predominantly solid "streaming" pattern reminiscent of florid hyperplasia. However, there are hyalinized fibrovascular cores, which are unusual and hyperplastic lesions. Often, the epithelial population will form pseudo rosettes with palisading around small vascular spaces, another finding which is extremely uncommon in benign proliferations. The epithelial cells have relatively small monotonous nuclei; however, mitoses are not difficult to identify. Cytoplasm may be eosinophilic and granular or there may be intracytoplasmic mucin with signet ring cells. As least a third of the lesions are associated with nearby papillomas, and it is possible to identify pagetoid growth of in situ carcinoma cells into adjacent ducts and papillary lesions. Special stains for chromogranin or synaptophysin will be positive in nearly all cases. Apart from papilloma and florid hyperplasia, solid papillary carcinoma bears some resemblance to solid variants of adenoid cystic carcinoma, which also grow as large cellular nests within collagenous stroma. The cells in these tumors have a "basaloid" appearance, however close inspection will reveal that they are biphasic tumors. Within the large cellular nests, one may observe small, inconspicuous intercalated ducts admixed with myoepithelium and small collagenous spherules. Finally, the rounded circumscribed nests of solid papillary carcinoma are remniscent of dramatic examples of LCIS, an impression further supported by the monotony of the cell population. However, LCIS lacks fibrovascular septa. Solid papillary carcinoma is strongly ER positive, unlike carcinoid metastases. Solid papillary carcinoma develops in older age groups and they are characterized by low grade malignant behavior. In three series of cases, the mean patient age was over 70. Maluf et al. had follow-up on 20 cases, one of which developed distant (lung) metastases. One of 12 cases in the series by Tsang et al. recurred. None of the patients in either series had nodal metastases. We have recently studied a series of 50 solid papillary carcinomas (see Qureshi et al below), most of which were accompanied by invasive neoplasm, usually colloid but some with carcinoid-like features. Overall, 14% had axillary metastasis and 11% of patients died from disease, all of whom exhibited an invasive tumor component. References: Scopsi L, Andreola S, Pilotti S, Bufalino R, Baldini M, Testori A, Rilke F. Mucinous carcinoma of the breast. A clinicopathologic, histochemical, and immunocytochemical study with special reference to neuroendocrine differentiation. American Journal of Surgical Pathology 1994; 18(7):702-711. Tsang W, Chan J. Endocrine ductal carcinoma in situ (E-DCIS) of the breast. American Journal of Surgical Pathology 1996; 20(8):921-943. Cross A, Azzopardi J, Krausz T, van Noorden S, Palak J. A morphological and immunocytochemical study of a distinctive variant of ductal carcinoma in situ of the breast. Histopathology 1985; 9:21 -27. Maluf H, Koerner F. Solid papillary carcinoma of the breast. American Journal of Surgical Pathology 1995;19(11):1237-1244. Shin SJ, Rosen PP. Solid variant of mammary adenoid cystic carcinoma with basaloid features – a study of nine cases. Am J Surg Pathol 2002; 26(4): 413-420. Qureshi H, Nassar H, Visscher D. Clinicopatholgic analysis of solid papillary carcinoma of the breast. Mod Pathol. 2005: 18(suppl 1); 47A