Search

The clinicopathologic findings in 200 cases of malignant fibrous histiocytoma (MFH) with follow-up information are presented. This tumor occurred principally as a mass on an extremity (lower extremity 49%, upper extremity 19%) or in the abdominal cavity or retroperitoneum (16%) of adults (peak incidence 61-70 years of age). It typically involved deep fascia (19%) or skeletal muscle (59%) and only rarely was confined to the subcutis without fascial involvement (7%). The MFH had variable morphologic features and frequently showed transitions from areas having a highly ordered storiform pattern to less differentiated areas having a pleomorphic appearance. The rate of local recurrence of the tumor was 44%, and of metastasis, 42%. Metastasis was most frequently to the lung (82%) and lymph nodes (32%). Factors that influenced the rate of metastasis included depth, size, and inflammatory component of the tumor. Tumors that were small, superficially located, or had a prominent inflammatory component metastasized less frequently than larger, more deeply located tumors. In our experience the MFH is the most common soft tissue sarcoma of late adult life, and many tumors previously diagnosed as pleomorphic variants of liposarcoma, fibrosarcoma, or rhabdomyosarcoma are probably examples of MFH. Although the histogenesis of this neoplasm remains controversial, we feel it is best regarded as a primitive and pleomorphic sarcoma showing partial fibroblastic and histiocytic differentiation, as reflected by collagen production and occasional phagocytosis.

Intramuscular myxoma is a benign mesenchymal lesion consisting of bland spindled cells embedded in an avascular myxoid stroma. On CT, intramuscular myxoma presents as a well-demarcated, homogeneous, low density mass situated within skeletal muscle. The attenuation of the lesion is slightly greater than water but less than that of the surrounding normal muscle, with typical values between +10 and +60 HU. There is scant magnetic resonance (MR) literature on the appearance of intramuscular myxoma; the few MR spin echo images that have been published characterize it as a homogeneous mass with signal intensity less than or equal to skeletal muscle on T1-weighted and brighter than fat on T2-weighted pulse sequences. We present two cases of intramuscular myxoma with imaging characteristics that differ from those previously reported.

Twenty-six cases of a newly recognized form of vascular tumor are presented. The tumor may occur at any age, has a male predominance, and develops preferentially in the dermis and subcutaneous tissues of the distal extremities. Histologically it combines the features of both a cavernous hemangioma and Kaposi's sarcoma. It is composed of thin-walled cavernous vessels which may be dilated, partially collapsed, or filled with organizing thrombi and phleboliths. These areas are intimately associated with spindled areas reminiscent of Kaposi's sarcoma. The spindled areas differ from Kaposi's sarcoma by the presence of occasional epithelioid endothelial cells, which sometimes display vacuolization. Follow-up information in 14 cases indicates that nine patients experienced "recurrences." One patient, who also received radiotherapy, developed regional lymph node metastasis 40 years after diagnosis and following 19 recurrences. No patient, however, has died of his disease, despite relatively limited surgical excision. The term "spindle cell hemangioendothelioma" is suggested for this vascular tumor of low-grade malignancy.

A series of 102 benign osteoblastic tumors of multiple skeletal sites was reviewed, and on the basis of their clinical, radiologic, and pathologic features they were classified into three diagnostic categories: osteoid osteoma, osteoblastoma, and aggressive osteoblastoma. A historic review of the development of the nomenclature of benign osteoblastic tumors, with special emphasis on the evolving concept of aggressive and malignant behavior, is presented. Histologic criteria for the recognition of aggressive osteoblastoma are presented and illustrated in connection with the 15 cases so classified in the present series. The differential diagnosis of aggressive osteoblastoma and low-grade osteosarcoma is discussed. In defining the problem of differentiating locally aggressive osteoblastic lesions from potentially metastasizing tumors, the authors propose that four categories of these osteoblastic tumors can be defined: (1) Innocuous-appearing low-grade osteosarcomas that resemble osteoblastomas histologically. This mimicry accounts for most errors in diagnosis. (2) Rare osteoblastomas that have undergone spontaneous transformation into osteosarcomas. (3) Very rare, clinically and radiologically typical osteoblastomas that show pseudosarcomatous histologic features but pursue a benign course. (4) Locally aggressive osteoblastomas that are likely to recur, do not metastasize, and show characteristic and recognizable histologic features.

A clinicopathologic analysis of 28 cases of giant cell fibroblastoma (GCF), a rare mesenchymal tumor occurring predominantly in the first decade of life, is presented. This disease presented as a painless, slowly enlarging, subcutaneous mass. The tumor recurred locally in 47% of the patients; however, metastasis was not detected. On microscopic examination, GCF showed an unique combination of spindle cell patterns, pleomorphic and multinucleated giant cells, myxoid areas, and distinctive sinusoid-like spaces. This unrecognized histomorphologic picture led to a misdiagnosis of sarcoma in 40% of the cases. The histogenesis of this lesion remains uncertain; however, based on both clinical and morphologic similarities, it is proposed that GCF is a juvenile form of dermatofibrosarcoma protuberans (DFSP).

A 13-year-old female with biochemically proven alpha mannosidase deficiency (mannosidosis) developed a bilateral destructive synovitis of the ankle region, a hitherto unreported complication of this disease. Clinically, it was believed to be a pigmented villonodular synovitis. Histologically, the synovium was thrown into villous folds and was infiltrated with clear histiocytes having rare collections of PAS-positive, diastase-resistant material. Electron microscopy demonstrated numerous membrane bound vacuoles filled with granular, amorphous material. This lesion can be distinguished from pigmented villonodular synovitis by its bilaterally symmetrical distribution, the monomorphic population of cells, and the presence of material having the histochemical and ultrastructural properties of (neutral) oligosaccharides.

A typical calcifying epithelial odontogenic tumor of the maxilla was examined with the electron microscope. The tumor cell resembles the ameloblast at an early stage of enamel deposition. Formation of extracellular amyloid masses probably proceeds both by active cellular secretion and cell death, each process adding similar granulofibrillar material to these masses, which tend to calcify. The amyloid masses are probably a relatively homogenous protein material and represent a specific tumor cell product. Further characterization of this neoplasm must include chemical and physical studies of this extracellular tumor product, which is an amyloid material because of classic staining characteristics.

A case report presents a liposarcoma of the extremities and an overall review of this disease entity. Past and present histologic classifications of liposarcoma are discussed, as are the clinical behavior and treatment options in relation to the surgical stage of the tumor. The importance of a well-planned biopsy site is stressed.

It has been generally recognized that malignant fibrous histiocytoma (MFH) may assume a highly myxoid, hypocellular appearance. Eighty cases of malignant fibrous histiocytoma having varying degrees of myxoid change were reviewed. These tumors typically arose on the extremities (leg, 61%; arm, 21%) of adults (peak age incidence, 60-69 years). They were usually attached to fascia (31%) or involved skeletal muscle (51%) and had a mucoid or translucent appearance. The myxoid areas consisted of widely spaced spindled and pleomorphic cells embedded in a matrix of acid mucopolysaccharides. The cellular areas were indistinguishable from those of the typical pleomorphic MFH. The rate of local recurrence of these tumors was 61%, and of metastasis, 23%, but metastasis was less likely when the tumor was small, superficially located, or had a prominent myxoid component. In fact, the degree of myxoid change was inversely related to the rate of metastasis. Therefore, because of the more favorable prognosis of the myxoid variant, it seems appropriate to separate it from the usual nonmyxoid form of MFH. The myxoid variant must also be clearly distinguished from benign myxoid lesions such as myxoma or nodular fasciitis, with which it is often confused.

The clinical and pathologic findings of 16 examples of a distinctive stromal tumor of the breast designated as "myofibroblastoma" are reported. Eleven of the 16 patients were men, and the average age at presentation was 63 years. Fourteen were treated by local excision and two by simple mastectomy. None of the lesions recurred or metastasized. The tumors were grossly nodular and well-demarcated from the surrounding mammary tissue. Ducts and lobules were not engulfed by the neoplasm. Microscopically, the lesions were formed by uniform, slender, bipolar spindle cells haphazardly arranged in fascicular clusters separated by broad bands of hyalinized collagen. Ultrastructural examination of four lesions identified a predominance of myofibroblasts. Immunoreactivity for S-100 protein and cytokeratin was absent in the 10 tumors examined, but desmin immunoreactivity was focally present in three lesions. The differential diagnosis of myofibroblastoma includes reactive processes and benign neoplasms such as nodular and proliferative fascititis, fibromatosis, spindle-cell lipoma, neurofibroma, neurilemmoma, and leiomyoma. Malignant neoplasms such as stromal sarcoma, malignant fibrous histiocytoma, and spindle-cell or metaplastic carcinoma should not be confused with a myofibroblastoma. The clinical significance of this entity lies primarily in its recognition as a distinctive benign neoplasm.

Epithelioid hemangioendothelioma is a unique tumor of adult life which is characterized by an "epithelioid" or "histiocytoid" endothelial cell. Forty-one cases of this rare tumor have been recognized at the Armed Forces Institute of Pathology. They may occur in either superficial or deep soft tissue, and in 26 cases appeared to arise from a vessel, usually a medium-sized or large vein. They are composed of rounded or slightly spindled eosinophilic endothelial cells with rounded nuclei and prominent cytoplasmic vacuolization. The latter feature probably represents primitive lumen formation by a single cell. The cells grown in small nests or cords and only focally line well-formed vascular channels. The pattern of solid growth and the epithelioid appearance of the endothelium frequently leads to the mistaken diagnosis of metastatic carcinoma. The tumor can be distinguished from a carcinoma by the lack of pleomorphism and mitotic activity in most instances and by the presence of focal vascular channels. Ultrastructural study in four cases confirmed the endothelial nature of the tumor in demonstrating cells surrounded by basal lamina, dotted with surface pinocytotic vesicles, and occasionally containing Weibel-Palade bodies. Follow-up information in 31 cases indicated that 20 patients were alive and well following therapy; three developed local recurrences and six metastases. It is suggested the term epithelioid hemangioendothelioma be used to designate these biologically "borderline" neoplasms. The significance of the epithelioid endothelial cell is not entirely clear. Since it may be observed in both benign and malignant vascular lesions, its presence alone does not define a clinicopathologic entity.

Nine new cases of adamantinoma of long bone are presented. The age range, location, and symptomatology are similar to those in precious reports. Histologically most of the tumors have a "basaloid" or "spindled" pattern. A squamoid pattern with keratinization or an "angioblastic" pattern is seen less frequently. In all cases with adequate material there has been an associated frbrous dysplasia-like lesion is interpreted as being a part of the spectrum of mesenchymal differentiation of which the tumor is capable. Two cases in which metastasis occurred are compared to previously reported metastasizing cases. Few criteria are available that identify the potentially metastasizing tumor.

An unusual foreign body reaction to silica (quartz), resembling fibrous histiocytoma, is described in 7 patients (age range 22 to 71 years). These lesions occurred in the inguinal region (4 cases) or the abdominal wall (3 cases), and in 5 instances were associated with a history of injection at the same site 10 to 41 years previously. Most commonly the injection consisted of the administration of a sclerosing agent for the repair of a hernia. Microscopically these lesions contained broad sheets of histiocytes separated by bands or concentrically lamellated nodules of collagen. Intra- and extra-cellular birefringent crystals, identified by x-ray diffraction as silica (quartz), were present in all cases and served to distinguish this process from a true neoplasm. Although the injection therapy for hernia is now obsolete, it was formerly practiced in the United States with a variety of sclerosing agents including silica (quartz). Since these lesions are often confused with a benign or malignant fibrous histiocytoma it is recommended that fibro-histiocytic lesions associated with a previous hernia or injection at the same site be examined for the presence of silica.

A rare, distinctive neoplasm occurring in the soft tissue of the extremities and resembling chordoma has been recently described and variously termed "chordoid sarcoma," "chordoid tumor," and "parachordoma." An example of this tumor occurring in the flank is presented. The tumor lacks the ultrastructural features associated with chordomas. Moreover, the tumor appears to be elaborating an abundant matrix of sulfated acid mucopolysaccharide interspersed with collagen fibers in varying stages of maturation. These features suggest that the tumor is exhibiting chondroid, rather than chordoid, differentiation. Previous reports of extraskeletal myxoid chondrosarcoma bear a striking light microscopic and electron microscopic similarity to the "chordoid sarcoma," suggesting that the latter is a variant of extraskeletal myxoid chondrosarcoma.

We report 22 examples of an unusual and distinctive benign mesenchymal tumor arising exclusively from lymph nodes of the groin. The tumor, which presents clinically as a swelling, is composed of spindled cells arranged in solid sheets or short, vaguely palisaded fascicles similar to a neurilemoma. The spindled cells blend gradually with large mats of eosinophilic material that appear as thick bands, ellipses, or circular profiles, depending on the plane of section. These eosinophilic structures, which represent a highly characteristic feature of the tumor, contain deeply eosinophilic, collagen-rich cores surrounded by a weakly eosinophilic, actin-rich cuff. The actin within these eosinophilic structures is derived by coalescence of intracellular actin globules extruded from neighboring cells. In all cases, a thin, compressed rim of normal lymph node was identified. Immunohistochemical analysis indicates that the cells express actin but lack S-100 protein, synaptophysin, desmin, keratin, and epithelial membrane antigen. Delicate, linear striations were identified in only two cases by conventional histochemical techniques. The foregoing features suggest that the tumor is related to a myofibroblast or a specialized smooth-muscle cell. These tumors, therefore, probably arise from smooth-muscle-like cells, which are normally present in some lymph node capsules or stroma. Follow-up information on 17 patients indicated that all are alive and well without any evidence of recurrence or metastasis.

The pathology of an unusual form of nonneuropathic familial amyloidosis is presented. The disease, occurring in two sisters, is similar to a form of familial amyloidosis described by Ostertag in 1950 and is characterized by progressive renal failure and an autosomal dominant mode of inheritance. Widespread vascular amyloidosis and dense renal glomerular amyloid deposits characterize the disease pathologically. Renal interstitial foam cells and glomerular giant cells were found in the kidneys of one sister. The giant cells, probably of macrophage origin, contain amyloid fibrils within poorly formed non-membrane-bounded cytoplasmic vacuoles. Transitions to well-formed membrane-bounded cytoplasmic vacuoles with nonfibrillar material were also present. It is suggested that these cells function to degrade and resorb amyloid, and that as amyloid is changed to a nonfibrillar state, well-defined membranes can form around the degraded material.