Solid variant of aneurysmal bone cyst: a case report with bilateral involvement of the distal femoral metaphyses.

An extremely rare case of bilateral, symmetrical involvement of distal femoral metaphyses by the solid variant of aneurysmal bone cyst (ABC) in a boy aged 13 years is described. Although there is no difference between the conventional ABC and the solid variant in terms of clinical and radiological presentation, the lesion is solid, composed of fibrohistiocytic cells with abundant giant cells and/or areas of florid, heterotopic ossification, while aneurysmal channels are sparse or absent. The lesion needs to be differentiated from giant cell tumour of bone, when the osteoclastic component predominates, while fibrous dysplasia, osteoblastoma and even osteosarcoma need to be excluded any time ossification is prominent. Careful evaluation of the clinical, radiological and pathological findings is necessary.

Glomus tumor. A histological, histochemical and immunohistochemical study of the various types.

Glomus tumors are benign lesions composed of vessels and glomocytes in varying proportions. The histological appearance of the tumors depend upon the ratio of the vascular to the glomus cells and their differentiation as well as upon the amount and composition of the stroma. The aim of the present study was the establishment of criteria for the distinction of glomus tumor-like malformations from neoplasms with glomus cell differentiation. Using a panel of monoclonal and polyclonal antibodies (vimentin, a-smooth muscle actin, desmin, pan-keratin, low molecular weight cytokeratin, EMA, NSE, S-100 protein, Factor VIII, a1-ACT) glomus tumors could be separated into three types: vascular, cellular with myxoid stroma and cellular, solid type. In the first two types the tumor growth is composed of all three components found in normal glomus body, but in a haphazard fashion and thus might be considered as tumor-like malformations. The third type is composed of perivascular arranged cells most of which acquire the phenotypical characteristics of glomocytes. This last tumor probably represent the neoplastic variant of the group of lesions designated by the term glomus tumor.

Old ectopic pregnancy remnants with morphological features of placental site nodule occurring in fallopian tube and broad ligament.

Placental site nodule (PSN) is an asymptomatic benign proliferation of intermediate trophoblast from a previous gestation that failed to involute. It is most commonly found in the endometrium or endocervix; however, placental site nodule has recently been reported to occur at sites of ectopic gestation. This is the first case of PSN in the broad ligament in direct contact with the fallopian tube. The patient underwent surgery for an adenocarcinoma of the opposite tube. Microscopically and immunohistochemically, the lesion showed the characteristics of a proliferation of intermediate trophoblast.

Parachordoma. A case report of a very rare soft tissue tumor.

An extremely rare and peculiar soft tissue tumor is described. Few examples of this tumor are classified under the term parachordoma, while probably many more are designated as chordoid sarcomas. The tumor presents histological features similar to those of chordoma, as well as to extraskeletal myxoid chondrosarcomas (chordoid sarcomas), and should also be differentiated from chondroid syringoma or mixed tumor of the skin. The tumor reported herein appeared as a deep cited soft tissue mass, presenting the histology of chordoma in an extra-axial localization. On the other hand, the positive immunoreactions of the tumor cells with cytokeratin and epithelial membrane antigen (EMA) ruled out the diagnosis of chondrosarcoma. It seems, therefore, that this is a special type of soft tissue tumor with bimodal differentiation (epithelial and mesenchymal) with good prognosis.

Histological findings in breast tissue specimens from reduction mammoplasties.

Tissue specimens from 55 consecutive reduction mammoplasty operations were studied histologically for changes considered to be associated to an increased risk in the development of invasive breast cancer. A thorough sampling of all removed tissues was performed and nearly all solid parts were processed for histological evaluation. We found that in 47 specimens, most of which belonged to women younger than 40 years of age (39), both breasts presented either no-proliferative changes or mild hyperplastic lesions of the usual type and thus the women had no increased risk for breast cancer development. In 7 breast specimens, all of them from women older than 30 years, the changes observed ranged from florid hyperplasia to atypical ductal or lobular hyperplasia, which are lesions considered to be associated to a relatively increased risk of invasive carcinoma. Finally we present a case of infiltrative ductal carcinoma with extensive lesions of atypical hyperplasia and combined ductal and lobular carcinoma in situ in both breasts, which developed 3 years after reduction mammoplasty in which changes of atypical hyperplasia were found. We suggest that reduction mammoplasty specimens should be handled with particular care and according to the women's age.

Giant cell fibroblastoma: an entity or a reactive phenomenon?

The histological and immunohistochemical features of four tumors displaying the characteristic pattern of Giant Cell Fibroblastoma (GCF) are presented. Three of them were found in association with classical and/or myxoid dermatofibrosarcoma protuberans, while the fourth tumor was a retroperitoneal malignant hemangiopericytoma where foci with features of GCF were found. Typical sinusoidal spaces and the bizarre mononuclear and multinucleated cells in close association to blood vessels presenting a wide spectrum of lesions of their walls are also described. These last changes led us to believe that GCF-like lesions might not always characterize an entity but could often represent a host reaction of the connective tissue to locally aggressive or malignant tumors.

Extraskeletal Ewing's sarcoma of the parotid region: a case report with the detection of the tumour's immunophenotypical characteristics.

A case report of a malignant small round cell tumour of the parotid region, with features of extraskeletal Ewing's sarcoma is presented. Besides its rare location in the soft tissues of the parotid area, the tumour expressed focal NSE and desmin immunoreactivity, indicative of multidirectional differentiation.

Malignant peripheral nerve sheath tumor with glandular differentiation. Report of a case with emphasis to the usefulness of immunohistochemistry in the differential diagnosis.

A case of malignant nerve sheath tumor with glandular differentiation in a patient with neurofibromatosis is presented. In the spindle celled areas the tumor cells reacted strongly with vimentin and S-100 protein, while the glandular epithelia reacted with EMA, cytokeratins (peptides 8, 19, and 20) and CEA, as well as a few of them also with chromogranin. Based on the results of immunohistochemical profile of the tumor cells, the differential diagnosis of this rare soft tissue tumor from biphasic synovial sarcoma with glands, as well as its distinction from any other spindle cell sarcoma with entrapped skin appendages could be greatly facilitated.

Adult-type of rhabdomyoma of the cheek. A case report with emphasis on the histological and immunohistochemical features.

A case of adult-type rhabdomyoma of the cheek is reported. The tumor was composed of cells presenting striated muscle differentiation, which was confirmed immunohistochemically by the positive reaction with alpha 1-sarcomeric actin demonstrating the cytoplasmic cross striations. A careful evaluation of the light microscopic features of this rare tumor, as well as the histochemical and immunohistochemical characteristics of the tumor cells would greatly help the differential diagnosis.

Intraosseous lipoma. A report of three cases.

Intraosseous lipomas are considered to be among the rarest primary benign bone tumors. Lipoma developing in bone frequently presents evolutional changes, which in association with the lack of clinical information and the radiographic appearance of the bone lesion could be the main reasons for misinterpretation of the histological picture. We present three cases of intraosseous lipoma which developed in male patients aged 23, 34 and 35 years, involving the tibia (n = 2) and calcaneus (n = 1). The histologic pattern of all tumors was that of mature adipose tissue. The diagnosis was made by correlating the clinical and radiographic findings to those of light microscopy.