Immunohistochemical study of hormone receptor and hormone-regulated protein expression in phyllodes tumour: comparison with fibroadenoma

 The histogenesis of phyllodes tumour (PT) and that of fibroadenoma (FA) of the breast appear to be closely related. FA is thought to be hormonally responsive, while the hormone-responsiveness of PT is uncertain. To gain insight into hormone-responsiveness of PT, we performed immunohistochemical analysis of oestrogen-regulated pS2 and androgen-regulated prostate-specific antigen (PSA) protein expression and also of oestrogen receptor (ER), progesterone receptor (PgR) and androgen receptor (AR) expression in paraffin sections obtained from 50 female PT patients. Paraffin sections taken from 50 female fibroadenoma (FA) patients were analysed for comparison. ER, PgR, pS2, AR and PSA expression were detected in 32%, 96%, 20% 98% and 4.0% of PT sections and in 28%, 96%, 42% 80% and 10% of FA sections, respectively. No correlations were detected among ER, PgR and pS2 expression or between AR and PSA expression in PT or FA sections. PgR expression was significantly associated with AR expression in PT (P<0.0001). The present investigations indicate that PT and FA have almost similar hormone receptor status. However, different positivities of pS2 expression suggest that oestrogen-responsiveness may differ between PT and FA. In addition, a wide-ranging co-expression of AR and PgR in PT sections suggests that these receptors may play an important part in the proliferation, although the functional significance of these receptors should be elucidated. Received: 26 January 1998 / Accepted: 5 April 1998     

Androgen receptor expression in ductal carcinoma in situ of the breast: relation to oestrogen and progesterone receptors

AIMS: Ductal carcinoma in situ (DCIS) of the breast has been diagnosed increasingly since the advent of mammographic screening. In contrast to the situation in invasive breast carcinoma, there are no reports on androgen receptor (AR) status in DCIS and few reports on oestrogen (ER) and progesterone (PR) receptors. METHODS: AR expression was examined in 57 cases of DCIS of the breast and correlated to the degree of differentiation and ER/PR status using immunohistochemical methods. RESULTS: AR positivity was noted in 19 of the cases, whereas the other 38 cases were negative. There was no significant association between AR expression and the degree of differentiation of DCIS; three of the 13 well differentiated DCIS cases, 10 of the 19 intermediately differentiated cases, and six of the 25 poorly differentiated cases were positive (p = 0.093). However, a strong association was shown between the expression of ER (p < 0.0001) and PR (p = 0.002) and the degree of differentiation of DCIS. In addition, no significant association was found between the expression of AR and the expression of ER (p = 0.26) or PR (p = 0.57) in DCIS of the breast. CONCLUSIONS: A large number of cases of DCIS of the breast express AR and this may be associated with apocrine differentiation, which may impact on accurate typing of DCIS. Moreover, the expression of AR (but not ER or PR) in DCIS does not appear to be associated with the degree of differentiation.     

Expression of the pS2 peptide in primary breast carcinomas: Comparison of membrane and cytoplasmic staining patterns

The pS2 protein is oestrogen-regulated in breast cancer cell lines. Previous studies have shown a relationship to oestrogen receptor in primary breast carcinomas. This study examined 178 breast carcinomas for pS2 using immunohistochemistry. A high frequency (77 per cent) of positive tumours was found, using a 10 per cent cut-off point to define a positive tumour. There was no relationship with menopausal status or node status, a significant association with differentiation, a weak association with oestrogen receptor, and no association with progesterone receptor or overall survival. Two patterns of cellular localization were observed: cytoplasmic and membrane. The former showed a stronger relationship with oestrogen receptor status, although there were oestrogen receptornegative tumours with marked pS2 staining. Membrane staining showed a stronger relationship with differentiation, with a staining pattern similar to that observed for milk fat globule membrane. The staining patterns observed may support a role for pS2 in a secretory mechanism. However, the expression and function of pS2 in breast carcinomas emain complex, and are not simply related to oestrogen regulation.     

pS2 (TFF1) expression in prostate carcinoma: correlation with steroid receptor status

pS2 or TFF1 is a member of the trefoil factor family, which is distributed throughout the gastrointestinal tract in both normal and diseased tissues. It is also considered to be one of the major estrogen‐regulated proteins and an indicator of estrogen receptor (ER) functionality. pS2 has previously been investigated in benign and malignant prostate lesions with little information about its relationship to steroid receptor status. Our purpose was to correlate pS2 expression with steroid receptor status (ER alpha and progesterone receptor (PR)) and other pathologic variables in prostate carcinoma. 15 benign prostate hyperplasia (BPH) and 47 prostate carcinoma cases were investigated by means of immunohistochemistry for pS2, ER and PR expression. 80% of BPH showed pS2 cytoplasmic immunoreactivity in hyperplastic acini and about half of these cases also exhibited nuclear staining decorating basal or both basal and luminal nuclei. pS2 was highly expressed in prostate carcinoma (91.4%) with both cytoplasmic and nuclear patterns of staining. The latter pattern was significantly associated with carcinoma having a low Gleason score (p=0.02). pS2 lacked any significant correlation with steroid receptor status, stage or grade. Univariate survival analysis revealed a significant impact of stage (p=0.03) and nodal status (p<0.0001) on patient outcome. The diagnostic value of pS2 expression in prostate carcinoma validated 74.19% accuracy, 91.48% sensitivity and 78.18% positive predictive value. The high sensitivity of pS2 expression in prostate carcinoma could make it a suitable marker for diagnosis of prostate carcinoma, especially in metastatic cases of unknown origin. The absence of correlation and dissimilarity in immunolocalization between pS2 and ER alpha leads to the assumption that ER alpha could not be the regulatory protein for pS2 and may raise questions about the functionality of ER alpha in prostate. The nuclear pattern of pS2 immunoreactivity either in benign or malignant prostatic lesions is similar to the published data on ER beta distribution and could also identify a subset of carcinoma patients with a favorable prognosis.     

Expression of androgen,estrogen, and progesterone receptors in salivary gland tumors. Frequent expression of androgen receptor in a subset of malignant salivary gland tumors

The expression of sex hormone receptors in some tumors suggests a role for these receptors in tumor pathogenesis and therapy. Previous studies of the expression of estrogen and progesterone receptors in salivary gland tumors have reported conflicting results. We evaluated the immunohistochemical expression of androgen, estrogen, and progesterone receptors (AR, ER, and PR) in a series of 78 formalin-fixed, paraffin-embedded salivary gland tumors. Immunoreactivity for AR was seen in 14 of 14 carcinoma ex pleomorphic adenomas, 6 of 6 salivary duct carcinomas, and 2 of 2 basal cell adenocarcinomas but in only 2 of 10 acinic cell carcinomas, mucoepidermoid carcinomas, and adenoid cystic carcinomas each. AR expression was distributed evenly between the sexes. ER and PR were expressed in only a few cases of salivary gland tumors. All 26 benign salivary gland tumors were negative for AR, ER, and PR. The uniform expression of AR exclusively in a subset of malignant salivary gland tumors suggests a possible role for AR in the histogenesis and possibly in the clinical management of these malignant salivary gland tumors.     

Down-regulation of bcl-2 expression is closely related to squamous differentiation and progesterone therapy in endometrial carcinomas

To clarify whether changes in bcl-2 protein (bcl-2) expression are directly linked to differentiation, an immunohistochemical investigation was carried out on areas of squamous differentiation within 38 endometrial carcinomas (25 grade 1 and 13 grade 2 cases) as well as eight grade 1 carcinomas after progesterone therapy. Such areas of altered differentiation were subdivided into foci of squamous metaplasia (Sq-M) and morules. Expression of oestrogen and progesterone receptors (ER and PR) and cell proliferation were also examined. Immunoreactivity scores for bcl-2 in Sq-M foci were significantly lower than in the surrounding tumour regions, in line with reduced staining for ER and PR and Ki-67 labelling indices (LIs), while morule values were intermediate. After progesterone therapy, a marked decrease in bcl-2 immunoreactivity was found in the response group, along with low Ki-67 LIs and tumour cell maturation. These results indicate that in endometrial carcinoma, down-regulation of bcl-2 expression may be closely linked with squamous differentiation, in line with changes in ER and PR expression, as well as in cell proliferation. In addition, bcl-2 expression appears to be down-regulated by progesterone therapy through tumour cell maturation, indicating that bcl-2 may be a clinically useful marker of hormone therapy effects. © 1997 John Wiley & Sons, Ltd.     

Evaluation of ER, PR, MIB-1, pS2, and nuclear grade in FNA specimens of cT1 breast carcinomas: clinicopathological correlation

Objectives were to determine oestrogen (ER), progesterone receptors (PR), and antigen related to ER (pS2) and to characterize their relationship with the cellular proliferation marker MIB-1 and the nuclear grade (NG) of the cancer cells, using fine-needle aspirates (FNA), as well as the evaluation of their clinical usefulness. The expression of ER, PR, pS2, and MIB-1 was preoperatively detected by immunocytochemistry in FNAs of 70 patients with breast adenocarcinoma and clinical tumor size up to 2 cm. The NG of the tumor cells was also assessed in these samples. We analyzed whether there was any correlation between these biocytologic markers and the invasion of ipsillateral axillary lymph nodes (LN), which were histologically identified after standard surgical treatment in each case. Of the 70 patients 50, 42.85, 50, and 41.42% were positive for ER, PR, pS2, and MIB-1, respectively. Only NG alone was strongly related to the invasion of the LN (P < 0.001). All the patients with NG1 (100%) tumors presented free LN, whereas the majority of those with NG3 (72.72%) had invaded LN (P < 0.001). Patients (14.28%) with NG1 expressed MIB-1, 85.71% ER or PR, and 71.42% pS2. Among the MIB-1-positive tumors a high proportion of NG3 (65.51%) was observed. This finding underlined a relationship between MIB-1 and NG (P < 0.05), identifying an aggressive cancer type. Remarkably 93.33% of the patients with positive MIB-1 and invaded axilla had NG3, whereas 66.66% of them expressed ER or PR and 40% pS2. The findings of the present prospective, multivariate study indicate that NG of the tumor cells, obtained from the preoperative FNAs of breast cancer patients, is a strong predictive marker for the axillary status and in parallel with MIB-1 expression can with sufficient accuracy be of clinical utility. ER, PR, or pS2 on the other hand did not show any relation to the LN status and were not dependent to NG or MIB-1.     

Prolactin receptor expression in gynaecomastia and male breast carcinoma

Aims:  Despite the well-established function of prolactin (PRL) in normal breast development, its role in breast cancer pathogenesis is still controversial. PRL activity is dependent on the activation of a transmembrane protein, the PRL receptor (PRLR). The aim was to evaluate and compare PRLR expression in gynaecomastia and male breast carcinoma (MBC).
Methods and results:  PRLR expression was detected immunohistochemically in 30 cases of gynaecomastia and 30 cases of MBC. The whole series was also assessed for oestrogen receptors (ER), progesterone receptors (PR) and androgen receptors (AR). A cut-off of 10% was used as the criterion for positivity. Histological type and tumour differentiation were evaluated. Pathological stage was assessed [Tumour Node Metastasis (TNM)-International Union Against Cancer system]. Statistical analysis was performed with Fisher's exact test. PRLR positivity was seen in 20% of gynaecomastia cases and in 60% of MBC cases ( P  = 0.003). In gynaecomastia immunoreactivity was predominantly observed in luminal cell borders, whereas in MBC the reactivity was heterogeneous and mainly cytoplasmic. There was no statistically significant correlation between PRLR expression and ER, PR, AR, pTNM, or histological grade.
Conclusions:  PRLR is significantly more expressed in MBC than in gynaecomastia, and with different patterns of reactivity, suggesting a role for PRL in male breast carcinogenesis.     

The expression of ERα, ERβ and PR in lobular carcinoma in situ of the breast determined using laser microdissection and real-time PCR

Aims:  To determine the status of oestrogen receptor (ER) subtypes (ERα and ERβ) in lobular carcinoma in situ (LCIS) of the breast.
Methods and results:  Forty-seven cases of LCIS and six cases with normal breast lobules were subjected to immunohistochemistry and evaluated for ERα, ERβ and progesterone receptor (PR) expression. mRNA for ERα, ERβ1 and ERβ2 were quantified in LCIS and normal lobules using laser microdissection coupled with real-time polymerase chain reaction. LCIS showed a higher level of steroid receptor protein expression than normal lobules. There was no difference in ERβ1 gene or ERβ protein expression between normal lobules, pure LCIS, or LCIS associated with invasive breast cancer. No significant difference in expression of either ERα or ERβ was found between pure LCIS and LCIS associated with invasive cancer. However, PR was significantly lower in those cases of LCIS with associated invasive than in those without synchronous invasive disease.
Conclusions:  Increased expression of steroid receptors in LCIS suggests their possible role in the biology of LCIS and, for PR, could influence the predisposition of women diagnosed with LCIS to develop invasive breast carcinoma .     

Hormone receptors in non-malignant meningiomas correlate with apoptosis,cell proliferation and recurrence-free survival

AIMS: A retrospective immunohistochemical and statistical analysis of patients with non-malignant meningiomas was undertaken to determine the correlation of steroid hormone receptor status with apoptosis, tumour cell proliferation, clinicopathological characteristics and prediction of recurrence. METHODS AND RESULTS: Paraffin sections from 51 primary intracranial totally resected benign and atypical meningiomas were immunohistochemically evaluated for the expression of progesterone (PR), oestrogen (ER) and androgen (AR) receptors, apoptotic rate, Bcl-2, p53 and Ki67 antigens. In addition to the above parameters, the mitotic index and the patients' clinicopathological data were statistically correlated and entered in a recurrence-free survival analysis. A high level of apoptotic cell death was associated with loss of PR expression by logistic regression analysis (P = 0.016). An inverse correlation existed between the mitotic index and PR counts (P = 0.009), while high Ki67 values correlated with increased ARs (P = 0.041). Atypical meningiomas had a lower ER staining score (P = 0.036). Multivariate analysis indicated that the absence of PR and large tumour size were significant factors for shorter disease-free intervals. CONCLUSIONS: The results suggest that ER expression is lost or reduced in atypical meningiomas, whereas loss of PR expression is an indicator of increased apoptosis and early recurrence. PRs and ARs may also influence tumour cell proliferation.     

Expression of oestrogen receptor-beta in apocrine carcinomas of the breast

AIMS: Apocrine carcinoma of the breast seldom expresses oestrogen receptors (ER) or progesterone receptors (PR), but frequently expresses androgen receptors (AR). Because of this unusual hormone receptor status, it has been suggested that oestrogens have a less important role in the pathogenesis of apocrine carcinoma. The ER status of apocrine carcinoma has been studied for one kind of ER, the classic receptor now named ER-alpha; however, the status of ER-beta, a secondary oestrogen receptor, has not been examined systematically in apocrine carcinoma. The aim was to study ER-beta status in apocrine carcinoma. METHODS AND RESULTS: The expression of ER-beta was examined immunohistochemically in 48 apocrine carcinomas and compared with clinicopathological factors and ER-alpha, PR and AR status. ER-beta positivity was observed in 35 cases (73%), regardless of any clinicopathological factors or the status of other receptors. The results of ER-beta mRNA analysis supported the immunohistochemical results. CONCLUSIONS: The significance of oestrogens in apocrine carcinoma should not be dismissed at present when the role of ER-beta remains to be determined. Studying the action of oestrogen or antioestrogen in apocrine carcinoma may reveal a role for ER-beta independent of ER-alpha and raise the potential of hormonal therapy for these tumours.     

Endometrial carcinoma: association of steroid hormone receptor expression with low angiogenesis and bcl-2 expression

In endometrial tissues, malignant change may be accompanied by a loss of hormone dependence which is, usually, reflected in a parallel loss of oestrogen and progesterone receptors (ER and PR). In this study, the steroid receptor status of 164 endometrial carcinomas was related to intratumoural angiogenesis and the apoptotic proteins bcl-2 and p53. Relationships to conventional histopathological features and patient survival were also sought. Immunohistochemistry was performed on formalin-fixed, paraffin-embedded tissues. The mean follow-up was 55 months (range 19-167 months). Specific nuclear staining for ER and PR was detected in 35% and 32% of endometrial carcinomas, respectively, and was very commonly co-expressed (P<0.0001). The failure of demonstrating a steroid receptor complement in endometrial neoplasms was, in general terms, an adverse prognostic sign. Thus, ER or PR loss was significantly associated with non-endometrioid carcinomas (ER P=0.01; PR P=0.004) and with deep myometrial invasion (ER P<0.0002), high intratumoural angiogenesis (PR P<0.01) and the absence of bcl-2 expression (PR P<0.005). There was a trend for patients with ER or simultaneous ER/PR expression to have an improved survival, but this association did not reach the level of statistical significance. In multivariate analysis (all stages), tumour cell type (endometrioid versus non-endometrioid carcinomas) and stage of disease were the only variables associated with prognosis (P=0.01 and P<0.0001, respectively), with tumour cell type retaining its independent prognostic value and within stage-I endometrial carcinomas (P=0.02). It is suggested that the loss of steroid hormone receptors in endometrial carcinomas is associated with a more aggressive phenotype and the switching-on of angiogenic pathways.     

Immunohistochemistry of pS2 in normal human breast and in various histological forms of breast tumours

Expression of pS2 was studied by immunocytochemistry in normal breast tissue ( n = 20), benign tumours ( n = 9) and 145 breast cancers representative of the different histological types. pS2 immunostaining was scored as negative (D1 = 0-5% stained cells), positive (D2 = 5-75% stained cells) or highly positive (D3 > 75% stained cells). pS2 protein was evident in all normal breast samples examined. Six of nine benign lesions showed pS2 staining. In both cases, immunostaining was weaker than in breast cancers. Of breast cancers, 77/145 (53.1%) were pS2 positive, including 33.1% with intense staining. The presence of pS2 was not correlated with the age of patients, the size of the primary tumour, or lymph node status, but was correlated with histological grading and nuclear grading. pS2 expression was also correlated with menopausal status and oestrogen receptor status (59% of receptor-positive tumours were pS2 positive), but not to progesterone receptor status. pS2 expression in breast carcinomas is not a characteristic of specific histological types. Although this protein is predominantly expressed in oestrogen receptor-positive and differentiated tumours, it shows oestrogen-independent expression in about 30% of cases.     

Steroid hormone receptor in pleural solitary fibrous tumours and CD34+ progenitor stromal cells

Solitary fibrous tumours (SFT), originally described in the pleura, were subsequently recognized in numerous extrapleural sites. This suggests that a common stem cell, present in various organs and tissues, may be at the origin of SFT and that specific factors may be involved in the proliferation of such cells. Recently it has been described that steroid hormone receptors, progesterone receptors in particular, are expressed by extrapleural SFT. In addition, progesterone may participate as growth factor in many CD34(+) stromal neoplasms, which express low levels of the hormone receptors. The present study analysed the expression of androgen (AR), oestrogen (ER) and progesterone (PR) receptors in a series of 32 pleural SFT, 10 mesotheliomas and in reactive tissue of chronic pleuritis. ER and AR were never expressed by SFT or by chronic pleuritis, whereas PR were demonstrated in 2/16 "large" (>8 cm) and in 6/16 "small" (< or =8 cm) pleural SFT (all expressing CD34, bcl-2 and CD99). PR(+) SFT had a significantly higher proliferative activity (p = 0.04) (Ki-67 mean value 6.5%) and lower p27(kip1) (mean value 51.5%) expression than the PR(-) cases (Ki-67 mean value 3.81% and p27(kip1) mean value 57.86%). One of the cases expressing a high level of PR (80%) recurred 1 year after first surgery and the recurrence was PR(+) as well, but with a lower percentage of nuclear receptor expression (12%). In addition, in chronically inflamed subserosal tissue, a subpopulation of CD34(+) endothelial and interstitial dendritic cells was identified, which also expressed PR. These findings suggest that the CD34(+) submesothelial interstitial dendritic cells, activated during reactive processes, may be the stem cells that give rise to SFT, and that progesterone might participate in the growth of SFT through modulation of its specific receptors.     

Immunohistochemical demonstration of androgen receptor in breast cancer and its relationship to other prognostic factors

Androgen actions and androgen receptors (ARs) have been described in human breast cancer cells both in vivo and in vitro. With the use of a new monoclonal anti-AR antibody, AR was immunohistochemically demonstrated in 76 primary breast cancers. Positive immunostaining was found in 79 per cent of tumours. Benign ductal epithelium was often AR-positive whereas the tumour stroma lacked AR immunoreactivity. At the subcellular level, nuclear localization was evident using either cross-linking (Zamboni's fluid) or precipitating (acetone) fixatives on frozen sections. The use of archival paraffin-embedded tissue yielded negative results. A significant association was found between expression of AR and oestrogen receptor (ER) (P=0.0006) determined immunohistochemically on adjacent sections. Most progesterone receptor (PR)-negative cases were also AR-negative (P=0.02), but significant proportion (38 per cent) of AR-positive tumours did not contain PR. Unlike ER, AR was not associated with aneuploidy or erb-B2 oncogene overexpression, and was only marginally associated with tumour proliferation rate (S-phase fraction by DNA flow cytometry). In conclusion, the close association of AR with ER and PR suggests that immunohistochemical determination of androgen receptors may have value as a prognostic factor and/or predictor of response to endocrine therapy.     

Expression of androgen receptors in benign and malignant endometrial stromal neoplasms

Several studies have shown that endometrial stromal neoplasms express estrogen and progesterone receptors (ER, PR). To our knowledge, the presence or absence of androgen receptors (AR) in these rare uterine neoplasms has not been investigated. Tumors (n=20)—3 endometrial stromal nodules, 14 low-grade endometrial stromal sarcomas (ESS, low grade), and 3 high-grade endometrial sarcomas (undifferentiated endometrial sarcoma, UES)—were studied. Immunohistochemical analyses for ER, PR, and AR were performed on formalin-fixed, paraffin-embedded archival material. Positive immunoreactions for ER and PR were observed in 14 (70%) and 17 (85%) cases, respectively. Furthermore, 9 cases (45%) were positive for AR. Among 17 ESS and UES cases, 7 (41%) revealed positivity for AR. Two of three benign stromal nodules were also positive for AR. Moreover, one of the three high-grade sarcomas (undifferentiated endometrial sarcoma) was negative for both ER and PR, but showed positive reaction for AR. In summary, ARs are expressed in 45% of endometrial stromal neoplasms. In addition to determination of ER and PR, the results of immunohistochemical examination of AR in these rare uterine tumors may have some impact on the postoperative management of the patients.     

Ovarian steroids and the human breast: regulation of stem cells and cell proliferation

Ovarian steroidal control of mammary gland proliferation and differentiation is not well defined in the human. We therefore developed the athymic nude mouse model in which intact normal human breast tissue is xenografted subcutaneously and treated with human physiological serum levels of oestrogen (E) and/or progesterone (P). We showed that: (i) E, and not P, is the major steroid hormone inducing proliferation of epithelial cells in the adult non-pregnant, non-lactating breast; (ii) E induces progesterone receptor (PR) expression; and (iii) PR expression is maximally induced at low E concentrations while a higher amount of E was required to induce proliferation. Using double label immuno-fluorescence, we demonstrated that cells expressing the oestrogen receptor- (ER) invariably contained the PR but that steroid receptor expression and cell proliferation (Ki67 antigen) were dissociated. Recently, we have demonstrated that some ER/PR-positive epithelial cells are quiescent breast stem cells suggesting that they act as “steroid hormone sensors” that secrete paracrine factors to regulate the proliferative activity of adjacent ER/PR-negative epithelial cells. The dissociation between steroid receptor expression and cell proliferation in normal epithelium was lost at an early stage in ER/PR-positive breast tumour formation perhaps indicating that they arise from deregulation of the normally quiescent breast stem cells.     

Adenoid cystic carcinoma of the breast: a tumour commonly devoid of oestrogen receptors and related proteins

AIM: Adenoid cystic carcinoma (ACC) of the breast is an uncommon well-differentiated tumour with good prognosis, and sometimes difficult to distinguish from in-situ and invasive cribriform carcinoma (ICC) which are relatively more common. Recently, we encountered a case of ACC that proved to be totally oestrogen receptor (ER) negative by immunohistochemistry. We investigated the possibility that this may be a consistent feature that can help in differentiating ACC from ICC which are usually ER positive. METHODS AND RESULTS: The immunoperoxidase technique was used to study the expression of ER and other related proteins in six cases of ACC and two cases of ICC. All ACC cases were negative for oestrogen (ER) and progesterone (PgR) receptors whereas the two ICC were strongly positive for ER and showed a variable degree of PgR positivity. In addition, ACC cases were pS2 negative and showed minimal expression of prolactin receptors (PrlR), while the two ICC showed widespread and strong staining for pS2 and PrlR. The percentages of cells staining positively for Ki67 and p27 were generally lower in ACC than in ICC. Both tumour types were c-erbB-2 negative, but p53 was weakly to moderately positive. CONCLUSIONS: The findings suggest that a negative immunoperoxidase staining for ER would confirm the diagnosis of ACC in contrast to the positive staining which is always seen in ICC. The findings also raise the issue of the presence of a specific class of ER negative breast carcinomas which are negative not because of poor differentiation, but because of their derivation from, or differentiation along, an ER negative cell lineage.