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Solitary fibrous tumor (SFT) is usually an indolent neoplasm with a low rate of local recurrence and metastasis. Although dedifferentiation of low-grade sarcoma is well documented, the concept of dedifferentiated SFT was not recognized until recently. A case of intracranial SFT with seven recurrences within 5 years, showing progression and dedifferentiation during the course of disease, is reported here. A 51-year-old woman with a history of irradiation during infancy presented with a SFT in the right posterior fossa. Because of the close proximity to the brain stem, the tumor could not be removed completely. The tumor recurred 12, 16, and 28 months after the initial operation. With the repeated recurrences, cellularity, mitotic count, and Ki-67 (MIB-1) index increased gradually. The histology suddenly changed at the fourth recurrence, which occurred 16 months after postoperative radiation therapy for the third recurrence. The tumor revealed a fibrosarcoma-like appearance with necrosis and markedly increased mitotic activity. The tumor further recurred 50, 52, and 55 months after the initial operation with the same fibrosarcoma-like histology. The patient died of uncontrolled tumor 58 months after the initial operation. In this case radiation may have played some role in the tumorigenesis, progression, and dedifferentiation of the SFT., (© 2010 The Authors. Pathology International © 2010 Japanese Society of Pathology and Blackwell Publishing Asia Pty Ltd.)

Herein is described a unique case of breast carcinoma with two different types of giant cells noted in both cytological and histological specimens. A 51-year-old Japanese woman noticed a hard mass in the upper outer quadrant of her left breast. Aspiration cytology exhibited numerous anaplastic giant cells; the cytological diagnosis was high-grade ductal carcinoma, although a few osteoclastic giant cells were also observed. A left simple mastectomy and sentinel lymph node biopsy were performed. Histologically, approximately 90% of the tumor was composed of giant cells; conventional invasive ductal carcinoma and ductal carcinoma in situ were found focally at the periphery of the tumor. The main part of the tumor contained both anaplastic, neoplastic giant cells and non-neoplastic, osteoclastic giant cells that were distinguishable from nuclear atypism. The presence of the two types of giant cells was also confirmed on immunohistochemistry using a histiocytic marker (CD68) and two epithelial markers (AE1/AE3 and CAM5.2). Based on the latest World Health Organization classification, the diagnosis was pleomorphic carcinoma with osteoclastic giant cells. To the authors' knowledge there has been no previous report on this subject except for a single case mentioned in Rosen's Breast Pathology.

Breast cancer can be classified into several subtypes based on gene expression profiling. Basal-like breast carcinoma (BLC) has a triple negative phenotype, that is, the subtype lacks the estrogen receptor (ER), progesterone receptor (PgR) and human epidermal growth factor receptor 2 (HER2). It has been recently reported that CD109, a glycosylphosphatidylinositol (GPI)-anchored cell surface protein, is a new breast myoepithelial marker. In the present study CD109 expression was investigated in invasive ductal carcinomas (IDC) of the breast on immunohistochemistry. Eighty-eight formalin-fixed, paraffin-embedded breast carcinoma sections were immunostained with anti-CD109, anti-cytokeratin 5/6 (CK5/6), anti-calponin, anti-vimentin and anti-p63 antibodies. CD109 expression was detected in 18 of 30 basal-like breast carcinomas (BLC) but not in other types of 53 IDC (non-BLC) that were positive for ER, PgR and/or HER2. The percentage of CD109-positive tissues (60%) in BLC was similar to that of CK5/6 (63%) and higher than that of other myoepithelial markers including p63 (23%), calponin (33%) and vimentin (33%). Statistical analysis indicated that the CD109-positive group in BLC, but not the CK5/6-positive group in BLC, was associated with reduced fat invasion (P < 0.05). These findings indicate that CD109 is a useful diagnostic marker for BLC and that CD109 expression may affect biological properties of cancer cells.

The CD109 gene encodes a glycosylphosphatidylinositol (GPI)-anchored cell surface protein. Herein it is shown that CD109 is highly expressed in myoepithelial cells of mammary, salivary, and lacrimal glands; and in prostate basal cells. The anti-CD109 antibody generated by the authors was available for formalin-fixed paraffin section, and it strongly stained myoepithelial cells and basal cells but not ductal, acinar, and secretory cells in these glands. CD109 expression was negative in examined breast ductal carcinomas and prostate adenocarcinomas. These findings indicate that CD109 is a useful marker for the diagnosis of invasive breast and prostate carcinomas.

Papillary breast lesions remain a source of diagnostic confusion because the full range of epithelial proliferations may arise within, or secondarily involve, papilloma. The expression of p63 and high-molecular-weight cytokeratins (HMWCK) was studied simultaneously in 33 papillary lesions including intraductal papilloma (IP, n = 10), atypical papilloma (AP, n = 8) and intraductal papillary carcinoma (IPC, n = 15) by double immunostaining. The myoepithelial cell nuclei were stained dark brown whereas the cytoplasms of usual ductal hyperplasia (UDH) and myoepithelium were stained purple. The myoepithelial layer was recognized as a dark brown dotted line at the epithelial stromal junction in all IP (10/10), most AP (7/8) and some IPC (7/15), suggesting that the retained myoepithelial layer in the papillary processes does not necessarily guarantee benignity. However, the malignant epithelial cells in AP and IPC were typically recognized as monotonous populations unstained with either chromogen. These monotonous cells contrasted with the proliferating cells of UDH in papilloma, which had intense purple cytoplasm in a mosaic-like fashion. The present data suggest that the double immunostaining with the two popular antibodies p63 and HMWCK is a useful tool for reproducible classification of papillary breast lesions.

Acinic cell carcinoma of the breast is an uncommon neoplasm. Since the first case of this rare variant of breast carcinoma was reported in 1996, only 10 cases have been reported in the English-language literature. Reported herein is the first case of primary acinic cell carcinoma of the breast in a Japanese woman. To the naked eye, the tumor appeared well circumscribed and the cut surface was grayish-pink and hemorrhaging. Microscopically, the tumor was predominantly made up of a monotonous proliferation of cells with a finely granular cytoplasm, resembling acinic cells of the parotid gland. Some neoplastic cells had a clear cytoplasm. In spite of extensive sampling, no common histological patterns of breast carcinoma such as in situ and invasive ductal carcinoma were recognized in the present case, indicating that the present case was pure acinic cell carcinoma. In addition, the immunohistochemical profile of this tumor was identical to that of the acinic cell carcinoma of the salivary gland: estrogen receptor, progesterone receptor, HER2 and cytokeratin (CK)20 were negative and amylase and CK7 were positive. The patient has been well for 22 months since the wide local excision of the tumor and no signs of salivary neoplasm are evident to date.

Pulmonary capillary hemangiomatosis is a rare vascular proliferative disease of unknown etiology. The common clinical features are slowly progressive and finally fatal pulmonary hypertension. The clinical diagnosis is usually difficult. Because most reported cases are of autopsy, little is known about its incipient lesion and natural history. Presented herein is a case of pulmonary capillary hemangiomatosis incidentally detected in a surgically resected lung for a metastatic colon cancer. The patient was a 60-year-old Japanese woman with a history of sigmoid colon cancer 3 years previously. The patient had undergone a right lower lobectomy for a metastatic tumor in the hilar region and a thoracoscopic tumorectomy of the peripheral area of the left upper lobe. Except for an episode of hemoptysis 2 weeks prior to the lung surgery, there were no other clinical symptoms characteristic of pulmonary capillary hemangiomatosis. The non-tumor area of right lower lobe showed multiple foci of capillary proliferation affecting alveolar walls, interlobular septa and pleura associated with patchy hemorrhage. There was a minor degree of vascular and bronchial involvement by capillary proliferation. It is suggested this particular case is an incidentally detected clinically incipient stage of pulmonary capillary hemangiomatosis. Passive congestion secondary to metastatic colon cancer in the hilar region may have contributed to the pathogenesis of this lesion.

Signet ring cell carcinoma and glassy cell carcinoma are both rare histological subtypes of uterine cervical cancer. This report is of a case of uterine cervical carcinoma arising in a 29-year-old woman who had major components of signet ring cell carcinoma and glassy cell carcinoma within the same tumor. Histochemical and immunohistochemical analyses, including high and low molecular weight cytokeratins, p63 and MUC5AC, additionally demonstrated the squamous and adenocarcinomatous differentiation in the neoplastic cells, which showed otherwise unclassifiable morphology on the haematoxylin-eosin sections. A wide range of differentiation described above supports the speculation that glassy cell carcinoma may arise from the multipotential immature cells that can differentiate into both squamous and glandular cells. It would be precise to classify this tumor as adenosquamous carcinoma. Although adenosquamous carcinoma is not a rare histological subtype in the uterine cervix, it should be necessary to report the presence of glassy cells and signet ring cells when present because the presence of both components is associated with an unfavorable clinical behavior.

An unusual case of intraductal carcinoma of the breast arising in sclerosing adenosis is reported. A 49 year old Japanese woman noticed a lump in her right breast 3 years before she sought medical advice. Histologic examination of the lumpectomy specimen showed, adjacent to intraductal papilloma, sclerosing adenosis involved in a neoplastic cellular proliferation with cribriform pattern and comedo necrosis. Immunohistochemical study with anti-actin antibodies discriminated intraductal carcinoma from adjacent sclerosing adenosis by highlighting myoepithelial components in the latter. Extensive sampling revealed no carcinoma outside the sclerosing adenosis, implying that the intraductal carcinoma did originate in the tubules of sclerosing adenosis. A review of the literature indicated that the ductal to lobular ratio among carcinoma in situ concurring with sclerosing adenosis is about 1:2. The average age of patients with ductal and lobular carcinoma in situ in sclerosing adenosis is 39 and 43.7, respectively. It is suggested that carcinoma in situ arising in sclerosing adenosis and fibroadenoma have a similar biological basis.

Infarction of a breast fibroadenoma usually occurs in young females during pregnancy or lactation. This report describes a rare case of the total infarction of a fibroadenoma in a 58 year old postmenopausal woman. The chief complaint was a rapidly enlarged, slightly painful lump. Medullary carcinoma was suspected on palpation and mammography. Microscopically, the tumor was composed of a coarsely lobulated necrotic mass invaginated into an epithelial lined cyst. This was interpreted as an infarcted intracanalicular fibroadenoma, although the possibility of an infarcted phyllodes tumor cannot be entirely excluded. The significance of this rare event is the possible confusion with carcinoma. Extensive search for viable tissue is essential for the confirmation of the diagnosis.