Solid papillary carcinoma of breast: an ultrastructural study

Cytological study of 44 cases with solid papillary carcinoma and a systemic review of solid papillary carcinoma and neuroendocrine tumor of the breast

BACKGROUND

Solid-papillary carcinoma (SPC) of the breast is a rare variant of low-grade in situ and invasive carcinoma but there are only a few of the cytologic studies.

METHODS

We examined 44 cases of SPC of the breast to define the cytologic features. We also made a systemic review of reported cases of SPC and neuroendocrine tumor (NET) of the breast.

RESULTS

Both of our and the reviewed cases with SPC were very similar in the cytologic finding. It included hypercellularity, highly discohesive clusters, numerous isolated cells, small nuclei, finely granular chromatin of salt-and-pepper appearance, inconspicuous nucleoli, low nuclear-cytoplasmic ratio, and a plasmacytoid appearance. Moreover, SPC and NET had frequently all of these features in common. Capillary vessels structures and mucinous substance were not frequently seen in our and the reviewed cases with SPC. Rosette and pseudorosette were very rare in the cytologic specimen. The immunocytochemistry with our 9 cases with SPC indicated diffuse positivity for chromogranin A and/or synaptophysin.

CONCLUSION

Many cytologic features are frequently shared by SPC and NET of the breast. However, the vascular structure may not be a precise criterion for SPC. Rosette and pseudorosette are rarely helpful for the cytologic diagnosis.

Gross Cystic Disease Fluid Protein-15 (GCDFP-15) Expression Characterizes Breast Mucinous Carcinomas in Older Women

The predominant histological subtype of breast mucinous carcinoma in older women is type B (hypercellular type), and, in younger women, it is type A (hypocellular type). The characteristics of mucinous carcinomas of the same histological subtype may differ between older and younger women. This study aims to systematically clarify the pathological/immunohistochemical features of mucinous carcinomas. A total of 21 surgical cases of mucinous carcinoma (type A/B: 9/12 cases) in the older group (≥65 years) and 16 cases (type A/B: 14/2 cases) in the younger group (≤55 years) (n = 37) were included. Gross cystic disease fluid protein-15 (GCDFP-15) and eight other markers were used for immunostaining. The GCDFP-15-positive rate in the older group was high regardless of the histological subtype (type A, 77.8%; type B, 91.7%). The GCDFP-15 positivity in the older group was significantly higher than that in the younger group (p < 0.001 for Allred score). Among type A, GCDFP-15 positivity was significantly higher in the older group than in the younger group (p = 0.042 for the Allred score and p = 0.007 for the positivity rate). The present results suggest that GCDFP-15 expression characterizes mucinous carcinomas in older women.

Papillary neoplasms of the breast-reviewing the spectrum

Papillary neoplasms of the breast encompass a wide range of tumor types ranging from the benign intraductal papilloma to in situ and invasive papillary carcinomas. In this review, we considered each tumor entity listed under the Papillary Neoplasms category in the latest WHO Classification of Breast Tumors (5th edition), namely intraductal papilloma, papillary ductal carcinoma in situ, encapsulated papillary carcinoma, solid-papillary carcinoma, and invasive papillary carcinoma. We examined their pathological features, current issues pertaining to diagnosis and prognostication, as well as the latest molecular findings. We also briefly addressed adenomyoepithelioma and the newly included tall cell carcinoma with reversed polarity, highlighting areas where they overlap with papillary neoplasms.

Solid papillary carcinoma of breast; a detailed clinicopathological study of 65 cases of an uncommon breast neoplasm with literature review

Solid papillary carcinoma (SPC) is an uncommon breast tumor whose prognosis depends on invasive component. We studied clinicopathological features of SPC by reviewing 65 cases. Invasive component was seen in 75.4% cases. Almost all tumors with grade III nuclei had invasive component. Mean patients' age of invasive tumors was significantly higher than that of non-invasive tumors (P = .036). All patients were alive and disease free except for a single patient who developed distant metastasis and died of disease. SPC have excellent clinical course. Careful search for invasive component is mandatory, especially in tumors with older patient's age and higher nuclear grade.

Expression of glycolysis-related proteins in solid papillary carcinoma of the breast according to basement membrane status

PURPOSE

The aim of this study was to investigate the differences of expression in glycolysis-related proteins such as Glut-1, carbonic anhydrase (CA) IX, and monocarboxylate transporter (MCT) 4 according to the myoepithelial cell (MEC) and basement membrane (BM) status in solid papillary carcinoma (SPC) of the breast.

MATERIALS AND METHODS

Immunohistochemical evaluation of Glut-1, CAIX, and MCT4, as well as p63 and type IV collagen, were performed on 23 SPC cases.

RESULTS

Six and nine cases of SPC showed the presence and absence of myoepithelial cells, respectively, and eight cases belonged to the borderline status (p63-positive MEC on some areas of the outer tumor surface but not in others). BM was partially or completely absent in 14 cases and present in nine cases. SPC lacking BM more frequently showed high expression of CAIX than SPC with BM (p=0.037).

CONCLUSION

In SPC of the breast, a strong expression of CAIX seems to be associated with an increasing degree of loss of BM, which can be interpreted as BM degradation due to the induction of extracellular acidity with increasing expression of CAIX.

Synchronous bilateral solid papillary carcinomas of the breast

We herein report a case of synchronous bilateral solid papillary carcinoma of the breast. A 73-year-old female had a mass that was detected in the right breast on mammography. An ultrasound examination revealed one intracystic tumor in the right breast and two tumors in the left breast. A fine-needle aspiration biopsy of these three tumors was performed, which revealed a diagnosis of malignancy. A magnetic resonance imaging examination of the breasts showed diffuse small nodules surrounding these tumors bilaterally. Bilateral partial mastectomy and a sentinel lymph node biopsy were performed. Lymph node metastasis was detected in the right axilla, and additional lymph node dissection was performed. The pathological diagnosis was synchronous bilateral breast cancer, invasive ductal carcinoma NOS of the right breast, mucinous carcinomas of the left breast, and bilateral SPCs. A wide range of surgical margins were positive for SPCs, and additional bilateral total mastectomy was then performed. To the best of our knowledge, little is known about synchronous bilateral SPCs. Our case indicates that some SPCs can be widely scattered and make up a variety of invasive carcinomas. It is difficult to make a correct preoperative evaluation in such cases.

Solid papillary carcinoma of the breast: a pathologically and clinically distinct breast tumor

Solid papillary carcinomas are tumors morphologically characterized by round, well-defined nodules composed of low-grade ductal cells separated by fibrovascular cores. These tumors are rare and affect predominantly older women. Although they are considered in situ carcinomas, debate and uncertainty still exist regarding their true nature, because immunohistochemistry for myoepithelial cells has shown absence of myoepithelial cell layer along the epithelial-stromal interface of the tumor in many cases. Clinically, these tumors present as a palpable, centrally located mass or as bloody nipple discharge. Pathologically, solid papillary carcinomas exhibit low-grade features, and often the tumors display neuroendocrine and mucinous differentiation. In the majority of cases an associated invasive carcinoma is present, with colloid and neuroendocrine carcinomas being the most common. The pathologic differential diagnosis is broad and ranges from benign to malignant lesions. The treatment for solid papillary carcinomas is surgical excision. When invasive carcinoma is not present, the prognosis is excellent.

Encapsulated Papillary Carcinoma of the Breast

Papillary lesions of the breast include a broad spectrum of entities, many of which can be diagnostically challenging for the pathologist. This article focuses on encapsulated papillary carcinoma, a recently proposed term used to describe papillary carcinoma occurring within a cystically dilated duct. Previously considered a variant of papillary ductal carcinoma in situ, the finding that these lesions typically lack myoepithelial cells at their periphery has raised questions about their true nature. This article presents a practical approach to the diagnosis of encapsulated papillary carcinoma with a review of its histologic mimics and clinical significance.

Use of Myoepithelial Cell Markers in the Differential Diagnosis of Benign, In situ, and Invasive Lesions of the Breast

Immunohistochemical markers for myoepithelial cells are commonly used to distinguish invasive from noninvasive lesions in the breast. The approach takes advantage of the fact that conventional invasive carcinomas lack surrounding myoepithelial cells, whereas nearly all benign lesions and in situ carcinomas retain their myoepithelial cell layer. Although conceptually straightforward, the interpretation of myoepithelial cell markers can be complicated by misleading patterns of reactivity (such as stromal or tumor cell staining) or lack of reactivity (due to reduced numbers of myoepithelial cells or variable antigenicity). In this article, we discuss the advantages and disadvantages of commonly used myoepithelial cell markers, their general utility in distinguishing invasive from noninvasive processes, and pitfalls in their interpretation. We also examine whether the detection of myoepithelial cells is helpful in the evaluation of papillary lesions, another common application. Myoepithelial cell markers can be diagnostically useful in the distinction of many benign, in situ, and invasive lesions, but they must be interpreted in conjunction with careful morphologic analysis.

Loss of myoepithelium is variable in solid papillary carcinoma of the breast

AIMS

Reports on the frequency of myoepithelial loss in solid papillary carcinoma (SPC) of the breast, an unusual variant of papillary carcinoma with a solid pattern of expansile growth, have been strikingly contradictory. The aim was to clarify the frequency of myoepithelial loss in cases of SPC diagnosed at our institution.

METHODS AND RESULTS

Eleven cases of SPC with available blocks or unstained slides were retrieved from the M. D. Anderson archives or obtained from outside contributors. Immunohistochemistry for smooth muscle actin (SMA) and p63 was evaluated on the circumscribed nests that appeared to be non-invasive by haematoxylin and eosin morphology. Three of the 11 cases (27%) were positive for both SMA and p63 at the periphery of all such foci, whereas eight cases (73%) lacked staining for both myoepithelial markers in at least one focus. Of these eight cases, one was diagnosed with only microinvasion, yet metastatic tumour resembling the circumscribed primary SPC was identified in two ipsilateral axillary lymph nodes.

CONCLUSIONS

SPC of the breast frequently lacks myoepithelial markers at the tumour-stromal interface in spite of a circumscribed non-invasive appearance. Metastases from such tumours are infrequent, but can occur in cases that lack myoepithelial marker expression by immunohistochemistry.

Papillary lesions of the breast: a review

Papillary lesions comprise a wide spectrum of lesions in terms of their clinical presentation, morphologic appearance, malignant potential, and clinical behavior. Their defining feature is that of a fibrovascular stromal core lined by epithelial and myoepithelial cells, attached to the wall of the duct and extending into the duct lumen. Papillary lesions are often diagnostically challenging both on core biopsy and in excision specimens. Much of the difficulty arises from the many different terminologies that are used to describe the various entities that are included under the umbrella term of papillary lesions. Separation of papillary lesions into categories with a meaningful clinical outcome is most appropriate; however, there is a relative paucity of well-designed outcome studies with substantial cohort numbers to provide information in this regard. We use a pragmatic approach to the classification of papillary lesions in our practice, as we will outline in this review. We will also discuss controversies surrounding papillary lesions and focus on management of these lesions on core biopsy and in excision specimens.

Cytological study of 20 cases of solid-papillary carcinoma of the breast

Solid-papillary carcinoma (SPC) of the breast is a rare variant of low-grade intraductal carcinoma but there are few cytological studies. We examined 20 cases of SPC of the breast, aged 31-80 (mean age 66.0 yr), to define the cytological features. In each of the cytological specimens, we could find both malignant and benign cytological features; the former were characterized by hypercellularity, highly discohesive clusters, numerous isolated cells, and severe overcrowding cells, while the latter were marked by small and bland nuclei, a low nuclear-cytoplasmic ratio, and inconspicuous nucleoli. Neither abnormal naked nuclei of tumor cell origin nor oval naked nuclei of myoepithelial cell origin were seen. We also reviewed the cytological findings of SPC as well as neuroendocrine carcinomas with intraductal components that had been reported and we concluded that the coexistence of malignant and benign features was the most characteristic cytological feature of SPC.

Solid papillary ductal carcinoma in situ versus usual ductal hyperplasia in the breast: a potentially difficult distinction resolved by cytokeratin 5/6

The solid papillary variant of ductal carcinoma in situ is an uncommon entity, which usually presents in the seventh or eighth decade and may be associated with invasive mucinous carcinoma. Solid papillary ductal carcinoma in situ (SP-DCIS) shares many morphological features with usual ductal hyperplasia (UDH) involving a papilloma: papillary architecture, solid growth, cellular streaming, and low-grade nuclear features. These similarities can make the distinction between these 2 entities challenging. Recent studies have demonstrated that immunohistochemical staining for cytokeratin 5/6 can distinguish UDH from conventional forms of ductal carcinoma in situ. Most of the epithelial cells of UDH express cytokeratin 5/6, but the tumor cells of ductal carcinoma in situ do not. We tested the hypothesis that the results of staining for cytokeratin 5/6 can distinguish UDH from the solid papillary variant of ductal carcinoma in situ. Immunohistochemical staining of 14 cases of SP-DCIS and 9 cases of UDH (4 involving papillomas) was performed using cytokeratin 5/6 antibody clone D5/16 B4. Strong cytoplasmic or membrane staining was considered positive. The hyperplastic cells in all cases of UDH showed strong staining for cytokeratin 5/6. The percentage of positive cells ranged from 50% to 80%. None of the SP-DCIS tumor cells stained for cytokeratin 5/6; however, many cases did show staining of occasional entrapped, benign epithelial, and myoepithelial cells. We conclude that the absence of strong cytokeratin 5/6 expression by SP-DCIS distinguishes it from its morphological mimic, UDH. Pathologists must guard against misinterpreting SP-DCIS as UDH in those cases in which the carcinoma cells engulf cytokeratin 5/6-expressing residual, native epithelial cells.

Clinicopathologic analysis of solid papillary carcinoma of the breast and associated invasive carcinomas

Solid papillary carcinomas (SPCs) are uncommon tumors composed of circumscribed large cellular nodules separated by bands of dense fibrosis. The aim of this study was to further elucidate the characteristics of SPC, the types and significance of invasive carcinomas associated with these tumors, and the long-term clinical outcome. Fifty-eight SPCs were analyzed (mean follow-up, 9.4 years). Cases were divided into three groups: 1) SPC only (32.7%), 2) SPC with extravasated mucin (8.6%), and 3) SPC with invasive components (58.7%) consisting of neuroendocrine-like (29.5%), colloid (23.5%), ductal not otherwise specified (14.5%), lobular (3%), tubular (3%), or mixed (26.5%). The mean age was 72 years. All were estrogen receptor positive and 86% were histologic grade 1. The total size of the tumor measured 0.3 to 15 cm. In the group with invasive carcinoma, the size of invasion was 0.1 to 4 cm. Axillary nodes were involved in 13% of the cases (6 of 46); all of these had an invasive component in the primary tumor. Local recurrence was seen in 5 patients, all from the group with invasive carcinoma. Overall, 11.7% died of their tumor, 1 to 4 years after diagnosis (mean, 2.3 years); none of them belongs to the group of noninvasive SPC. Five of the 6 patients who died of tumor had invasive components. The sixth patient who died with "metastatic signet-ring cell carcinoma" at 10 years was in the group of patients with SPC with extravasated mucin where the SPC lesion had prominent signet-ring cell features. In conclusion, SPCs are heterogeneous lesions that arise in older women and have an indolent behavior. Lymph node and distant metastases are uncommon and generally limited to cases with (conventional) invasive components.

Noninvasive papillary proliferations

The diagnosis of noninvasive papillary tumors begins with categorization of the lesions as macropapillary or micropapillary. Macropapillary lesions include papilloma, papillary carcinoma, and papilloma harboring carcinoma. Papillomas consist of a few broad fronds, abundant stroma, and an epithelium containing both luminal and myoepithelial cells. Papillary carcinomas have many irregular fronds, small amounts of stroma, and a uniform population of malignant glandular cells. Papillomas can give rise to both conventional ductal hyperplasia and carcinomas. One analyzes proliferations on the surface of a papilloma as one would analyze those in a duct. Proliferations within the stalk of a papilloma require especially careful attention; one must observe large masses of cells demonstrating both cytological and architectural atypicality and devoid of intervening stroma to make the diagnosis of low-grade ductal carcinoma in-situ involving the stalk of a papilloma. Micropapillary proliferations represent either ductal hyperplasia or ductal carcinoma in situ. The former shows slight dilatation of ducts, micropapillae of similar size and shape, maturation of cells, lack of dishesion and necrosis, and lack of cytological atypicality. Micropapillary ductal carcinoma in situ exhibits extreme dilatation of ducts and lobules, micropapillae varying in size and shape, lack of maturation, dishesion and necrosis, and cytological atypicality.

Expression of apocrine differentiation markers in neuroendocrine breast carcinomas of aged women

Neuroendocrine (NE) breast carcinomas are a rare entity in young women; however, their frequency increases in aged patients. The present work demonstrates that NE breast carcinomas in elderly women can also express an apocrine immunophenotype and analyzes the histological and clinical aspects of such differentiation. A selected series of 50 NE tumors (positive for NE markers in >/=50% of the cells) was tested for the immunocytochemical expression of gross cystic disease fluid protein-15 (GCDFP-15). The results demonstrated that about 50% of moderately (G2) and well-differentiated (G1) NE breast carcinomas (mucinous, solid papillary, and solid cohesive histotypes) coexpressed the apocrine marker. In these cases, specific mRNA for GCDFP-15 (PIP) and for chromogranin A (ChA) was demonstrated using in situ hybridization (ISH). Carcinomas of the alveolar subtype (G2) and poorly differentiated carcinomas (G3), including one case of atypical carcinoid, were pure NE carcinomas, devoid of apocrine differentiation. The steroid receptor status of these lesions was evaluated to test a possible involvement of androgen receptors in apocrine differentiation. We demonstrated that the level of AR and the mean age of patients at diagnosis were significantly higher in apocrine than in nonapocrine differentiated tumors. The histological grade and the expression of estrogen receptor (ER) significantly influenced the prognosis of these NE carcinomas, either pure or NE-apocrine differentiated. The most original result of our study is therefore the demonstration of a possible divergent apocrine differentiation of NE breast carcinomas that might be regulated by the activation of androgen receptors in elder patients. In addition, the possibility for using Chs or GCDFP-15 serum values in the follow-up of these patients, as demonstrated in two cases of the present series, can justify the immunophenotyping of the tumors.

Mucinous carcinoma of the breast with neuroendocrine differentiation

A case of mucinous carcinoma of the breast with neuroendocrine differentiation in an 89-year-old woman is presented. The patient presented with a rapidly growing right breast mass, which she had had for 2-3 years. The tumor, 15 x 8 x 5 cm, was located mainly in the upper outer quadrant. Light microscopy revealed a pure mucinous carcinoma of type B. Neuroendocrine differentiation was demonstrated by Grimelius stain and chromogranin A, as well as the presence of neurosecretory granules. The breast cancer cells were of luminal origin and had dedifferentiated to attain neuroendocrine properties.