Primary small cell (oat cell) carcinoma of the breast: report of a case and review of the literature

Radiological and Histological Clues in the Diagnosis of Solitary and Synchronous Breast Metastasis From Small Cell Lung Carcinoma

Breast metastases from small cell lung carcinoma (SCLC) are extremely rare. Although reports of breast metastases from SCLC exist, only three studies have reported solitary and synchronous breast metastases. Herein, we present a case of SCLC with solitary and synchronous breast metastases. This unusual case highlights the importance of the combined use of radiological and immunohistochemical features to accurately distinguish solitary metastatic SCLC from primary breast carcinoma or metastatic carcinoma of other types of lung cancer. It also emphasizes the importance of the differences between solitary metastatic SCLC and primary breast carcinoma or metastatic carcinoma of other types of lung cancer for the respective prognoses and development of appropriate therapeutic plans.

Evolution of an invasive ductal carcinoma to a small cell carcinoma of the breast: A case report

RATIONALE

Small cell carcinoma (SCC) is a rare subtype of breast cancer and presents a complex diagnostic and treatment challenge, due to paucity of data. To the best of our knowledge, most cases of breast SCC reported in the literature describe a de novo breast primary. Our case is unique as it describes the evolution of an invasive ductal carcinoma after treatment into a SCC of the breast.

PATIENT CONCERNS AND DIAGNOSIS

We report a case of a 53-year-old female, lifelong non-smoker, who initially presented with breast mass noted on self examination. Breast and axillary lymph node biopsy demonstrated a hormone receptor positive invasive ductal carcinoma with a metastatic T3 lesion.

INTERVENTION

She was treated with first-line palbociclib/letrozole with initial clinical response, and at progression was switched to capecitabine with no response. Repeat biopsy of the axillary lesion showed evolution of the tumor into a triple negative breast cancer. She was then treated with third-line paclitaxel and radiation therapy with good initial response. She eventually had further disease progression and presented with a new mediastinal lymphadenopathy causing SVC syndrome. Biopsy of this showed a small cell variant of breast neuroendocrine carcinoma. Due to the evolution of histology in this case, a retrospective review of her initial breast specimen as well as the second biopsy from the axilla was conducted which confirmed that the mediastinal lymphadenopathy was metastatic from the original breast tumor.

OUTCOMES AND LESSONS

We speculate that the initial treatment allowed a minority of treatment-resistant neuroendocrine cells to grow and become the dominant face of the tumor. Our patient had an excellent response to carboplatin/etoposide and consolidative locoregional radiotherapy but presented with an early intracranial recurrence. This is a similar pattern of metastases as seen in lung SCC and highlights a potential role for prophylactic cranial irradiation in breast SCC. Further studies are needed to better understand the biology and treatment of breast SCC which continues to present a challenge for clinicians.

TTF-1 Positive Primary Small Cell Carcinoma of the Breast: A Case Report and Review of the Literature

Primary small cell carcinoma of the breast (SCCB) is a rare tumor subtype comprising <0.1% of all breast carcinomas. Here we present a case of thyroid transcription factor-1 (TTF-1) positive SCCB that recurred within 3 years of diagnosis in the lung and lymph nodes. Given the small number of cases, no clear guidelines exist on the appropriate management of patients with these aggressive tumors. We present a case study and review the current literature to highlight the knowledge gaps and needs of patients with these rare tumors. A 50-year-old premenopausal woman with no family history, presented with a palpable right breast mass. Biopsy was consistent with primary SCCB that was poorly differentiated, positive for synaptophysin and chromogranin and TTF-1 and presence of ductal carcinoma in situ component showing neuroendocrine differentiation. Imaging with PET, CT, and MRI brain excluded any other sites of primary disease. She underwent a right lumpectomy with axillary lymph node dissection and was treated with adjuvant cisplatin-based chemotherapy and concurrent radiation therapy. Thirty-four months later, routine scans showed a new right lower-lobe lung nodule and an enlarged sub-carinal node that was proven to be poorly differentiated neuroendocrine cancer. This case report sheds light on a rarely described disease and provides a comprehensive approach to diagnosis and management. Primary SCCB is an extremely rare, aggressive form of breast cancer that is molecularly and histologically similar to SCLC. However, a review of the literature highlights recent mutational analyses that show important differences between these two cancer types, including an increase in PIK3CA mutations in primary SCCB. Further studies, including genomic analyses are needed to better define this malignancy and to develop a standard treatment.

Primary Neuroendocrine Carcinoma of the Breast: A Case Report

Primary neuroendocrine carcinoma of the breast is an extremely rare tumor. We present our experience of primary neuroendocrine carcinoma of the breast in a 76-year-old woman. Surgical biopsies from breast and axillary lymphadenopathy showed a neuroendocrine carcinoma. Immunohistochemical staining of tumor cells with GCDFP15, NSE and chromogranin were positive. Computed tomography scans of the chest and abdomen showed no lesion for metastasis or another primary origin. Adjuvant hormone therapy was given, since the tumor was immunohistochemically receptor positive.

Primary small cell carcinoma of the breast: Report of seven cases and review of the literature

Aims and background

The aim of the study was to analyze the clinicopathological characteristics, treatment modalities, and clinical outcome of patients with primary small cell carcinoma of the breast.

Methods

Fifty-three cases of primary small cell carcinoma of the breast were identified; 7 cases in this series and 46 from the English-language medical literature.

Results

There were 52 females and 1 male. The mean age was 53 years. Tumor size ranged from 1 to 18 cm (mean, 4.53). Axillary node metastasis was present in 61.7%. Only one patient had distant metastases at presentation. The presence of hormone receptors was reported in 24.5% of the tumors. Modified radical mastectomy was the most common surgical procedure and was performed in 50.9% of the patients. Adjuvant radiotherapy was administered to 39.6% of the patients, and 69.8% underwent chemotherapy. Thirteen percent of patients received adjuvant tamoxifen therapy. The mean follow-up was 20.75 months (range, 3–60), and 10 of 53 cases (18.9%) died of metastatic disease.

Conclusions

The prognosis of primary small cell carcinoma of the breast largely depends on the initial stage of the disease. Multimodality treatment including surgery, radiotherapy and chemotherapy seems to be the most appropriate strategy for early disease. Chemotherapy is usually unsuccessful in treating metastatic disease.

[Primary neuroendocrine tumors of the breast: a retrospective study of 21 cases and literature review]

PURPOSE

The aim of the present study was to discuss the epidemiology, clinical and pathologic features, treatment, and prognosis of primary neuroendocrine carcinomas of the breast.

PATIENTS AND METHODS

We report 21 cases diagnosed over a period of 12 years (1995-2011) at the university hospital of Sfax. A review of the clinical data with pathology and immunohistochemistry study was carried out for all the cases.

RESULTS

The average age was 62 years (34-86 years). At the time of the diagnosis, tumours were classified T1 and T2 (16 cases), N1 (11 cases) and M1 in two cases. The histological examination has shown 13 cases of solid neuroendocrine carcinoma, six cases of large cell type and two cases of atypical carcinoid. Grade I and II SBR were found in 18 cases. Eighty-one percent of the tumours were reactive for synaptophysin; all tumours were positive for chromogranin. Thirteen (61.9%) tumours were estrogen receptor-positive and 12 (57.5%) progesterone receptor-positive. Nineteen (90.5%) tumours were negative for HER2/neu. Overall five-year survival was 72.7%. All patients had surgical treatment with modified radical mastectomy in 13 cases. Adjuvant treatment was indicated according to histopronostic elements.

CONCLUSION

For primary neuroendocrine carcinoma of the breast, multivariate analysis identified three predictive factors for mortality: disease stage, histological grade and lymph node involvement.

A population-based analysis of outcomes for small cell carcinoma of the breast by tumor stage and the use of radiation therapy

Purpose

Primary small cell carcinomas of the breast (SCCB) are rare tumors with limited data on outcomes and treatment strategies. Using a population based approach, we aimed to study outcomes of SCCB and determine whether the use of radiation therapy is associated with better survival among patients with SCCB.

Methods

Using the Surveillance, Epidemiology and End Results (SEER) registry, we identified patients with SCCB between1973 and 2010. We examined the stage specific survival of these patients and compared it to the stage specific survival of small cell lung cancer (SCLC) from the SEER database over the same accrual period. We further analyzed the impact of radiation therapy on overall survival for SCCB patients using a univariate and multivariate approach.

Results

A total of 199 patients with primary SCCB with staging were identified during the study period. Eighty-four patients (42%) had localized disease, 77 (39%) had regional disease and 38 (19%) had distant disease. For comparison, 81,933 patients with SCLC were identified. Outcomes were superior for patients with SCCB with localized (150 vs. 16 months, p < 0.01) and regional disease (56 vs. 13 months, p < 0.01), but not distant disease (7 vs. 7 months, p = 0.43). Use of radiation therapy was not associated with a significant difference in OS for patients with either localized (202 vs. 147 months, p = 0.48) or regional (52 vs. 75 months, p = 0.650) disease.

Conclusions

SCCB has a more favorable prognosis by stage for localized and regional disease than SCLC. Adjuvant radiation is not associated with an improvement in survival for patients with localized or regional SCCB in this dataset.

Locally-advanced primary neuroendocrine carcinoma of the breast: case report and review of the literature

Background

Primary neuroendocrine carcinoma of the breast is a heterogeneous group of rare tumors with positive immunoreactivity to neuroendocrine markers in at least 50% of cells. Diagnosis also requires that other primary sites be ruled out and that the same tumor show histological evidence of a breast in situ component. Primary neuroendocrine carcinoma of the breast rarely presents as locally advanced disease and less frequently with such widespread metastatic disease as described herein. The review accompanying this case report is the first to provide an overview of all the cases of primary neuroendocrine carcinoma of the breast published in the literature and encompasses detailed information regarding epidemiology, histogenesis, clinical and histologic diagnosis criteria, classification, surgical and adjuvant treatment, as well as prognosis. We also provide recommendations for common clinical and histologic pitfalls associated with this tumor.

Case presentation

We describe a case of a 51-year-old Hispanic woman initially diagnosed with locally-advanced invasive ductal carcinoma that did not respond to neodjuvant treatment. After undergoing modified radical mastectomy the final surgical pathology showed evidence of alveolar-type primary neuroendocrine carcinoma of the breast. The patient was treated with cisplatin/etoposide followed by paclitaxel/carboplatinum. Thirteen months after surgery the patient is alive, but developed pulmonary, bone, and hepatic metastasis.

Conclusion

The breast in situ component of primary neuroendocrine carcinoma of the breast may prevail on a core biopsy samples increasing the probability of underdiagnosing this tumor preoperatively. Being aware of the existence of this disease allows for timely diagnosis and management. Optimal treatment requires simultaneous consideration of both the neuroendocrine and breast in situ tumor features.

Clinical features and treatment response of solid neuroendocrine breast carcinoma to adjuvant chemotherapy and endocrine therapy

Solid neuroendocrine breast carcinoma (solid NEBC) is a relatively uncommon malignant tumor of the breast. The purpose of our study was to explore the incidence and clinical features of this tumor, and to evaluate the efficacy of adjuvant chemotherapy and endocrine therapy for patients with solid NEBC. Of 7542 breast cancers registered during the period from March 2004 to April 2011, 22 patients (0.29%) who underwent surgery had tumors that were histologically confirmed as solid NEBC, and were enrolled in this study. The age range of these patients was 29-77 years (mean 52.5 years). Patients were staged according to the 7th edition of the pathologic tumor-node-metastasis (pTNM) staging system. Biopsies or resection specimens were reviewed and reclassified according to the World Health Organization (WHO) 2003 classification. We recorded clinical features including gender and age, chief complaint, and past medical history, tumor characteristics including size, location, preoperative diagnosis, and pathologic and immunohistochemical findings, the therapeutic schedule, and the follow-up results. Solid NEBC is a rare and distinct category of malignant disease of the breast, with good prognosis, and in most early-stage cases, is resectable. The role of adjuvant chemotherapy and endocrine therapy in solid NEBC may be limited and should be studied further.

Metastatic small cell neuroendocrine carcinoma of the breast

Cutaneous metastases from internal malignancies in women overwhelmingly emanate from the breast and typically exhibit features of an adenocarcinoma, although other histopathologic patterns may also be seen. Neuroendocrine breast carcinoma represents an uncommon variant of mammary carcinoma with fewer than 40 cases of the small cell subcategory reported. As with other small cell carcinomas, they may exhibit Merkel cell-like features and appropriate diagnosis of these tumor deposits often turns on clinical history and an appropriate immunohistochemical profile. Herein, we report the first known patient with cutaneous metastases from a small cell neuroendocrine breast carcinoma.

Does hormonal therapy have a therapeutic role in metastatic primary small cell neuroendocrine breast carcinoma? Case report and literature review

Primary neuroendocrine carcinoma of breast (NECB) is a very rare tumor; the World Health Organization(WHO) subcategorized these tumors into 3 major histologic subtypes: solid, small cell carcinoma (SMCC), and large cell NE carcinoma. The SMCC subtype is the least common and most aggressive and has been reported to be as aggressive as its pulmonary counterpart. SMCC is usually confirmed based on clinical, pathologic,and imaging studies. Local disease is usually managed in a fashion similar to that of the usual ductal breast cancer; in the metastatic SMCC setting, regimens that are implemented in small cell lung cancer are usually attempted, according to case reports and published small case series. Hormone receptors can be expressed in more than 90% of the solid tumor subtype; however its expression is manifested in about 50% of cases of SMCC. Although hormonal therapy can be used successfully to treat the usual metastatic ductal breast cancer,its utility in metastatic SMCC has not been reported. We report an impressive response to hormonal therapy in a patient with late relapse of breast carcinoma with a metastatic SMCC subtype that expressed hormone receptors. The response to hormonal therapy was sustained for about 12 months. The response to hormonal therapy is definitely an interesting finding that, to our knowledge, has not been described before in the setting of metastatic SMCC. We suggest considering adding hormonal therapy to the treatment pipeline for primary SMCC of the breast that express hormone receptors.

Primary mammary small-cell carcinoma: A case report and review of the literature

Only a few cases of primary small-cell carcinoma of the breast have been documented in the current medical literature. A confident diagnosis can only be made if a nonmammary site is excluded or if an in-situ component can be demonstrated histologically. These criteria have been met only in a very few of the published cases, including this case report. We describe a case of a 68-year-old lady with left breast lump, which was diagnosed as breast cancer on fine-needle aspiration and core biopsy. Metastatic workup was negative for disease elsewhere, and she received 3 cycles of neoadjuvant chemotherapy followed by surgery (modified radical mastectomy). However, the disease behaved very aggressively in the postoperative period. There is a lack of consensus regarding the management of the primary tumor. Present surgical treatment options are similar to those in cases of invasive ductal breast cancer, as appropriate for the size and stage of the lesion. A review of current literature on his rare entity is also presented.

Primary small-cell carcinoma of the breast: a case report

We report a case of small-cell carcinoma of the breast. The patient was a 54-year-old Japanese woman with a left breast mass. Mammography revealed a 1.2-cm microlobulated mass with partially ill-defined borders. Ultrasonography disclosed a hypoechoic mass measuring 1.8 × 1.2 × 1.2 cm with heterogeneous internal echoes and partially ill-defined borders. The shape of the mass was round and taller than it was wide in the orthogonal section to the longest axis of the mass. These imaging findings suggested a malignant tumor. Fine-needle aspiration cytology of the tumor also suggested a ductal carcinoma. Breast-conserving surgery was performed with axillary sentinel lymph node biopsy. A diagnosis of small-cell carcinoma of the breast was made based on the histologic and immunohistochemical findings. This rare breast tumor has been reported to be aggressive and associated with a poor prognosis; however, our patient is currently well and has had no clinical recurrence of the disease after 5 years of follow-up without radiotherapy or chemotherapy. Therefore, the prognosis may be better if the tumor is detected early and there is an absence of lymph node metastasis.

Ovarian nonsmall cell neuroendocrine carcinoma: a clinicopathologic and immunohistochemical study of 11 cases

Nonsmall cell neuroendocrine carcinoma (NSCNEC) of the ovary is a rare and aggressive tumor commonly associated with other surface epithelial and germ cell neoplasms. In this study, we present the clinicopathologic and immunohistochemical features of 11 such cases seen at The University of Texas M.D. Anderson Cancer Center in a 16-year period (1990 to 2005). Patients ranged in age from 22 to 63 years (mean 46.7). The most common presentation was abdominal/pelvic pain (6 cases), followed by ascites (2 cases), pelvic mass, vaginal bleeding, and abdominal bloating (1 case each). Tumors were mostly unilateral, cystic, or solid/cystic and ranged in size from 5 to 26 cm (mean 16.2). In 8 cases, NSCNEC was associated with other epithelial neoplasms, including mucinous neoplasms of low malignant potential, mucinous carcinoma, endometrioid carcinoma, mixed endometrioid and mucinous carcinoma, and a high-grade carcinoma, not otherwise specified. In 2 cases, the tumor was associated with a mature cystic teratoma; one of them also containing an invasive moderately differentiated adenocarcinoma. A single case was associated with a benign ovarian cyst. The latter case had a dermoid cyst in the contralateral ovary. NSCNEC represented anywhere from 10% to 90% of the ovarian tumor. Microscopically, the neuroendocrine component was usually composed of large and/or intermediate oval to round cells. In 2 cases, the intermediate cells were intermixed with small cells. Three cases had also spindle cells. The neoplastic cells were mostly arranged in a solid pattern, nests, or trabeculae. All tumors had a brisk mitotic activity. Immunoperoxidase studies for keratin cocktail, cytokeratin (CK) 7, CK20, CAM 5.2, chromogranin A, synaptophysin, NSE, CD56, and c-kit were performed and the cases stained as follows: keratin cocktail 6/6, CK7 4/5, CK20 3/5, CAM 5.2 3/3, chromogranin A 8/11, synaptophysin 9/9, NSE 1/1, CD56 4/8, and c-kit 5/7. According to the International Federation of Gynecology and Obstetrics staging system, 4 cases were stage I tumors, 3 cases were stage III tumors, and 4 cases were stage IV tumors. Seven patients were treated with total abdominal hysterectomy and bilateral salpingo-oophorectomy followed by chemotherapy. One patient had a bilateral salpingo-oophorectomy with omentectomy and appendectomy followed by chemotherapy; 1 patient had a total abdominal hysterectomy with right salpingo-oophorectomy followed by chemotherapy; one had a bilateral salpingo-oophorectomy followed by chemotherapy, and one had a right salpingo-oophorectomy with appendectomy followed by chemotherapy. Five patients died of disease at 2, 3, 9, 20, and 36 months. One patient is alive with disease at 8 months and 5 are alive without evidence of disease at 11, 28, 37, 66, and 68 months. Four of 5 patients who died of disease had either stage III or IV tumors and 3 of 5 patients who are alive without evidence of disease have stage I tumors. In summary, ovarian NSCNEC is an aggressive tumor with a tendency to present at advanced stage and cause death within a mean of 17 months after diagnosis; however, some patients, particularly those with stage I disease and/or those who have received platinum-based therapy, may have a more favorable prognosis.

[Oat cell carcinoma of the common bile duct]

Oat cell tumors in the common bile duct are extremely rare. We describe the case of a 76-year-old man with skin and mucous jaundice of 15 days' duration without constitutional syndrome. A tumor was diagnosed in the mid portion of the common bile duct. After surgical resection, pathological analysis revealed small-cell (oat cell) carcinoma. The treatment of these tumors is multidisciplinary. Surgery is followed by chemo- and radiotherapy.

Expression of CD117 (c-kit) receptor in dysgerminoma of the ovary: diagnostic and therapeutic implications

The proto-oncogene c-kit encodes a tyrosine kinase receptor, c-kit (CD117), which has been implicated in the development of a number of human malignancies. While the preferential expression of this protein has been well documented in testicular seminomas, there is little data concerning its expression in dysgerminomas of the ovary. We examined the expression of c-kit in 30 cases of ovarian dysgerminomas using immunohistohemical staining with a polyclonal anti-CD117 antibody. Staining was graded in a semiquantitative manner as follows: negative (no staining), 1+(1-10% staining), 2+(10-29% staining), 3+(30-50% staining), or 4+ (>50% staining). Of the 30 cases examined, 26 (87%) demonstrated immunoreactivity for CD117. In total, 10 (33%) demonstrated 4+ staining; 9 (30%) demonstrated 3+staining; 3 (10%) demonstrated 2+staining; 4 (13%) demonstrated 1+staining; and 4 (13%) demonstrated no staining. In conclusion, CD117 immunoreactivity was detected in 87% of ovarian dysgerminomas, a finding that correlates with previously reported frequencies of CD117 expression in seminomas (78-100%). Thus, antibodies to c-kit may be a useful diagnostic marker for ovarian dysgerminoma. Although the prognosis of patients with dysgerminoma is generally good, this receptor could potentially serve as a target for site-specific immunotherapy as an alternative and/or complement to conventional treatment options.

Solid variant of mammary "adenoid cystic carcinoma with basaloid features" merging with "small cell carcinoma"

We describe a rare case of a solid variant of a mammary adenoid cystic carcinoma with basaloid features (sbACC) and its coexistence with a "small cell" carcinoma (SCC), identified and confirmed by histological and immunohistochemical observations: the absence of glandular structures and PAS-positive globules, positivity for neuroendocrine markers (NSE, synaptophysin and chromogranin), and negativity for 34betaE12 and SMA actin were the aspects suggesting the presence of SCC. Furthermore, positivity for CD10 was found both in sbACC and in SCC, supporting the hypothesis that the two components share the same histogenetic myoepithelial origin and represent an example of dedifferentiation along neuroendocrine phenotype lines occurring in a multipotential neoplastic stem line, already committed towards a myoepithelial phenotype. To our knowledge, this is the first reported case of a solid basaloid adenoid cystic carcinoma merging with an SCC carcinoma. Furthermore, it is the first study in which CD10 was used to investigate the histogenesis of the two neoplastic components.

Small cell neuroendocrine carcinoma of the breast: a report of three cases and review of the literature

Small cell neuroendocrine carcinoma of the breast is a rare tumour with less than 30 cases reported in the literature. The clinicopathological findings of three cases of primary neuroendocrine carcinoma of the breast and a review of the pertinent literature are presented. The morphological and immunohistochemical patterns of this tumour are similar to its pulmonary counterpart. Expression of neuroendocrine markers is inconsistent, so morphology is the mainstay of diagnosis. Size is a very important prognostic factor in this tumour, as in breast carcinomas of the usual type.

Therapy, outcome and analysis of c-kit expression in patients with extrapulmonary small cell carcinoma

In this study, we aimed to investigate the clinicopathological characteristics with special emphasis on c-kit expression and the treatment results of patients with extrapulmonary small cell carcinoma (EPSCC). The medical records of the patients with EPSCC were reviewed, and the data regarding patient and tumour characteristics, treatment and clinical outcome were retrieved and analysed. A total of 28 patients with the diagnosis of EPSCC were identified. There were 19 males and 9 females, with a mean age of 56.5 years. Patients with limited disease (LD) (n = 13) were treated with surgery, chemotherapy (CT) and radiotherapy with different sequences. Patients with extensive disease (ED) (n = 15) were mainly treated with combination CT. The median overall survival was 14.5 months in patients with LD compared to 11 months in those with ED (p = 0.029). Ten patients (36%) showed c-kit overexpression. There was no significant difference between the survival of c-kit-positive and c-kit-negative patients (p = 0.367). In conclusion, our study demonstrates that the prognosis of EPSCC is poor despite currently available treatments. C-kit may be considered as a potential target for novel therapeutical approaches.

Fine-needle aspiration cytology of extramammary neoplasms metastatic to the breast

Fine-needle aspiration (FNA) biopsy is the first-line investigation in any breast lump and hence cytomorphological recognition of nonmammary metastatic tumors to the breast and their distinction from primary tumors is important. Metastatic breast neoplasms diagnosed over a 6-yr period from 1997 to 2002 were retrieved from the database of the Department of Cytopathology and the clinical, cytopathological, histochemical, and immunohistochemical findings were correlated with the histopathology of the primary tumor. Fifteen cases of metastatic breast neoplasms were encountered constituting 1.47% of all malignant tumors of the breast diagnosed on FNA. There were 14 female patients and one male patient aged 13-80 yr. The preaspiration clinical diagnosis was either a benign breast lump or a malignancy (primary vs. metastatic). The breast lump was the initial presentation in four cases and the cytodiagnosis of a metastatic malignancy lead to the subsequent detection of the primary malignancy. These included one case each of melanoma, myeloma, rhabdomyosarcoma, and small-cell carcinoma of the lung. There were five pediatric cases that included four cases of rhabdomyosarcoma and one case of leukemic deposit. The adult cases included two cases each of melanoma, small-cell carcinoma, and myeloma; one case of choriocarcinoma; and three cases of soft-tissue sarcomas. These included two cases of malignant fibrous histiocytoma (MFH) and one case of leiomyosarcoma. The presence of unusual cytomorphological patterns on breast FNA should alert the cytopathologist to the possibility of a metastatic breast neoplasm, even if not suspected clinically. A detailed history of the patient, clinical correlation, and immunocytochemistry helps in establishing an accurate diagnosis, which avoids unnecessary surgery and ensures appropriate treatment.

Prevalence of KIT expression in human tumors

PURPOSE

KIT is a target for imatinib mesylate (Gleevec; Novartis Pharma, Basel, Switzerland). Gastrointestinal stromal tumors (GISTs) express KIT and respond favorably to imatinib therapy. To determine other tumors in which such a molecular targeted therapy might be indicated, we investigated KIT expression in different human tumor types. Because recent studies in GISTs suggest that KIT-activating mutations predict response to imatinib therapy, we also sequenced a subset of positive tumors.

MATERIALS AND METHODS

More than 3,000 tumors from more than 120 different tumor categories were analyzed by immunohistochemistry in a tissue microarray format. Seven commercially available anti-KIT antibodies were initially evaluated. The antibody A4502 (DAKO) was selected for analysis because of a high frequency of positivity in GIST and low staining background in other tissues. To determine the frequency of KIT mutations in various tumor types, the exons 2, 8, 9, 11, 13, and 17 (where mutations previously were reported) were sequenced in 36 tumors with strong KIT expression.

RESULTS

KIT positivity was detected in 28 of 28 GISTs (100%), 42 of 50 seminomas (84%), 34 of 52 adenoid-cystic carcinomas (65%), 14 of 39 malignant melanomas (35%), and eight of 47 large-cell carcinomas of the lung (17%), as well as in 47 additional tumor types. KIT mutations were found in six of 12 analyzed GISTs, but only in one of 24 other tumors.

CONCLUSION

The results suggest that KIT expression occurs infrequently in most tumor types and that, with the exception of GISTs, KIT gene mutations are rare in immunohistochemically KIT-positive tumors.

Primary small cell neuroendocrine tumour of the breast

Primary neuroendocrine carcinomas of the breast are extremely rare. Tumours can only be considered small cell neuroendocrine tumour of the breast if nonmammary sites are excluded. These tumours form a diagnostic and therapeutic challenge. We present our experience of small cell neuroendocrine tumour of the breast and discuss a review of the relevant literature.

KIT (CD117)-Positive Breast Cancers Are Infrequent and Lack KIT Gene Mutations

PURPOSE

KIT (CD117) is a transmembrane tyrosine kinase representing a target for STI571 (Glivec) therapy. Some KIT-overexpressing solid tumors have responded favorably to STI571, potentially because of the presence of KIT-activating mutations.

EXPERIMENTAL DESIGN

To investigate the epidemiology of KIT overexpression and mutations, we investigated a series of 1654 breast cancers. All tumors were analyzed by immunohistochemistry in a tissue microarray format.

RESULTS

KIT expression was always present in normal breast epithelium. However, cancer analysis revealed the only 43 of 1654 (2.6%) tumors were KIT-positive. KIT expression was more frequent in medullary cancer (9 of 47 positive; 19.1%) than in any other histological tumor subtype (P < 0.001). KIT expression was significantly associated with high tumor grade (P < 0.0001) but unrelated to pT and pN categories or patient survival. Mutation analysis of exons 2, 8, 9, 11, 13, and 17 was negative in 10 KIT-positive tumors.

CONCLUSIONS

Overall, our data show that a high level of KIT expression occurs infrequently in breast cancer. KIT-positive breast cancers may not reflect "KIT up-regulation" because KIT is also expressed in normal breast epithelium. The lack of KIT mutations also argues against the therapeutic efficacy of STI571 in breast cancer.