Soft tissue giant cell tumor of low malignant potential: a proposal for the reclassification of malignant giant cell tumor of soft parts.

Although "giant cell tumor of soft parts" has traditionally been considered a single entity as reflected in the original term "malignant giant cell tumor of soft parts (MGCT)" and later by the term "malignant fibrous histiocytoma, giant cell type" the degree of atypia and mitotic activity varies in this group, suggesting biologic heterogeneity. The clinicopathologic features of 31 tumors meeting the traditional criteria of MGCT but having only mild to moderate nuclear atypia are presented. Patients with these tumors (19 females; 12 males) ranged in age from 14 to 84 years (mean, 40 years) and presented with masses of involving either superficial (n = 16) or deep (n = 13) soft tissue. Most occurred on the arm or hand (n = 16) and ranged in size from 0.7 to 6.5 cm (mean, 2.1 cm). The tumors consisted of sheets and nodules of rounded mononuclear cells that blended with spindled cells and benign osteoclastic giant cells. Pleomorphic giant cells were absent. Osteoid was noted in 10 cases, but features typically associated with tenosynovial giant cell tumors (such as dense stromal hyaline, siderophages, and xanthoma cells) were nearly always absent. Mitotic figures ranged from 1-10/10 HPF (mean, 2-3/10 high-powered field), and angiolymphatic invasion was present in 10 cases. Necrosis was absent, however. The mononuclear cells expressed CD68, tartrate-resistant acid phosphatase, and smooth muscle actin, but lacked CD45, S100 protein, desmin, and lysozyme, an immunophenotypic profile identical to that of giant cell tumor of bone. Follow-up information in 19 patients (mean, 3 yrs; median, 1-7 yrs) indicated recurrences in four patients, but none developed metastasis. This behavior contrasts significantly with the high-grade behavior traditionally associated with MGCT of soft parts. These giant cell tumors can be consistently recognized by the lack of cytologic atypia even in the face of mitotic activity and vascular invasion. Although their long term metastatic risk is not fully defined, we propose they be termed "giant cell tumors of low malignant potential" and regarded as the soft tissue analogue of giant cell tumor of bone. The term "malignant giant cell tumor of soft parts" or giant cell malignant fibrous histiocytoma should be restricted to histologically high-grade lesions.     

Fibrous dysplasia with degenerative atypia: a benign lesion potentially mistaken for sarcoma

Fibrous dysplasia is a benign disorder of bone in which proliferating fibrous tissue replaces the bony spongiosa. Cytologic atypia is generally not considered a feature of this proliferating tissue. We present a case of fibrous dysplasia with marked atypical nuclear changes consistent with degenerative or regressive changes. A 42-year-old man presented with an osteolytic lesion of the right iliac bone. Histologic study demonstrated a fibro-osseous lesion with woven bone trabeculae and bland-looking fibrous tissue. Several areas showed atypical cells with enlarged pleomorphic nuclei and bizarre features. There was no change in the nuclear-cytoplasmic ratio nor were mitotic figures identified. The differential diagnosis is discussed. When radiographic and other histologic findings suggest fibrous dysplasia, the atypical nuclear changes should not, by themselves, alter the diagnosis.     

Tumor der Peron?usloge

Degenerative nuclear atypia in mesenchymal neoplasia, especially in benign nerve sheath tumors, may become a pitfall leading to a wrong diagnosis of a sarcoma. Using a case of degenerative (ancient) schwannoma as an example, the characteristic findings of degenerative atypia are presented and discussed.     

Re-operation results in osteoarthritic change of knee joints in patients with giant cell tumor of bone

Giant cell tumor of bone occasionally results in secondary osteoarthritic changes in adjacent joints. The purpose of this study was to determine the factors associated with the development of degenerative arthritis in surgically treated patients with giant cell tumor of the distal femur or proximal tibia and the effect of residual subchondral bone thickness on the location of recurrent giant cell tumor. We retrospectively studied 30 patients with giant cell tumor of bone arising around the knee joint treated with intralesional curettage, high-speed burring, and electrocauterization, followed by filling with polymethylmethacrylate or autogenous bone graft. There was no significant difference in factors of age, gender, tumor location, residual thickness of subchondral bone, or Campanacci grade correlated with the recurrence. Of the 10 recurrence cases, seven recurred on the articular side, and three on the contra-articular side of the primary lesion. Less than 5 mm of residual thickness of subchondral bone was correlated with recurrence on the articular side (p=0.038). There were 10 cases (33.3%), in which secondary degenerative arthritic change developed or progressed. Re-operation for local recurrence or post-operative fractures was a significant factor correlated with the progression of secondary osteoarthritis (p=0.010). Less residual thickness of subchondral bone tended to be associated with secondary osteoarthritis (p=0.068). Other factors were not correlated significantly with osteoarthritic change. These data support the contention that the residual thickness of subchondral bone could be a factor predicting the location of recurrence, and operative procedure to avoid re-operation might be critical to preserve knee function.     

Malignant giant cell tumor of bone

Summary The fine structure of the different cell types constituting a primary malignant giant cell tumor of bone has been studied and the localization of acid phosphatase in relation to the subcellular organelles been demonstrated. Three distinct cell types with characteristic ultrastructural features were observed: giant cells, fibroblast-like cells, and cells with abundant lipid inclusions and mitochondria. Certain differences were noted between these three cell types and their counterparts in benign giant cell tumors of bone (described in a separate report). The enzyme histochemical and morphological data suggested that the giant cells in the malignant tumor might possess a more active and expansive lysosomal apparatus than corresponding cells in the benign variant.This investigation has been aided by a grant from the Swedish Cancer Society (grant 77:64, project No. 617-B77-06XA)     

Distribution of mucosubstances in adenoid cystic carcinoma

Summary Two unusual carcinomas of the breast are described, containing nests of infiltrating neoplasm situated within stromal lacunar spaces, and surrounded by numerous benign appearing multinucleated giant cells. Within the stroma, there was extensive hemorrhage, hemosiderin pigment deposition, and large numbers of mononucleated inflammatory cells. The morphology of both tumors resembled the giant cell tumor of bone. Although a similar giant cell reaction has recently been described in association with a uterine leiomyosarcoma, we are aware of only two other examples of this entity in the breast, both reported over 40 years ago in the French literature. This is the first report in which electron microscopy confirmed the benign histiocytic nature of the giant cells. These cells had many of the ultrastructural features of multinucleated giant cells described in tissue culture, skeletal osteoclastomas, and foreign body granulomas. We propose that the giant cells arise from fusion of mononucleated stromal cells, and most likely are reactive histiocytic elements which are in some way related to the tumor cell nests. Further studies of these unusual neoplasms are needed to determine if the giant cell reaction in any way affects the prognosis of the patient.     

Intrarenal schwannoma: a report of four cases including three cellular variants.

Renal schwannomas are extraordinarily rare neoplasms; only six have been reported, the majority of which occurred in the renal pelvis. We report the clinical and pathologic features of four additional cases. The resected kidney in all patients contained a well-demarcated, yellow-tan, smooth, and bulging intraparenchymal tumor (mean size, 9.7 cm; range, 4 to 16 cm). Microscopically, three cases were classified as cellular schwannomas, and one was a usual-type schwannoma, with degenerative nuclear atypia. By immunohistochemistry, all tumors were strongly S-100 protein positive and negative for pan-cytokeratin, CD57, smooth muscle actin, desmin, and CD34. Epithelial elements were not noted in the tumors, and there was no history of any clinical syndromes in these patients. Analysis of the four cases showed the mean age at presentation to be 47 years (range, 18 to 84 years), with no sex predisposition (two men, two women). Most patients were asymptomatic, and all received a diagnosis of renal cell carcinoma and treated as having such. Recognition and awareness of these rare, benign tumors will assist in the differential diagnosis of spindle cell tumors of the kidney and prevent their misdiagnosis as sarcomatoid carcinomas of the kidney or renal sarcomas. Our study, the largest series to date of renal schwannomas, demonstrates a predilection for the cellular variant in the kidney, documents that these tumors may present in the nonhilar region of the kidney, and provides clinical evidence of their benign biologic behavior.     

HISTOCHEMICAL, IMMUNOHISTOCHEMICAL AND ULTRASTRUCTURAL INVESTIGATIONS OF GIANT CELL TUMORS OF BONE

The origin and characteristics of so-called stromal cells (stromal cell) and the osteoclast-like giant cell series of 19 cases of giant cell tumor (G.C.T.) of bone were studied. Immunohistochemically, two interesting cases were found. The stromal cells of one case were α-1-antitrypsin positive and those of the other case were α-1-antichymotrypsin positive. The histiocytic stromal cells of the latter case seemed to be surely neoplastic since they showed mild to moderate cell atypism. There were foci consisting of fibroblastic cells or osteoid and osteoblasts within the tumor. Those cells in the foci were apparently continuous with the surrounding stromal cells, and they were, therefore, also considered to be neoplastic. These findings strongly indicate that the stromal cells originate from the undifferentiated mesenchymal cells in the bone marrow and may differentiate to osteoblastic, fibroblastic, and histiocytic cells. All cells of these three series were not stained for a high stable form of acid phosphatase (SAPhase). SAPhase activity was demonstrated only in osteoclast-like giant cells and some mononuclear cells, which are recently believed to be non-neoplastic. Therefore, the cell atypia of SAPhase negative stromal cells is considered to have a prognostic value.     

Histochemical, immunohistochemical and ultrastructural investigations of giant cell tumors of bone

The origin and characteristics of so-called stromal cells (stromal cell) and the osteoclast-like giant cell series of 19 cases of giant cell tumor (G.C.T.) of bone were studied. Immunohistochemically, two interesting cases were found. The stromal cells of one case were alpha-1-antitrypsin positive and those of the other case were alpha-1-antichymotrypsin positive. The histiocytic stromal cells of the latter case seemed to be surely neoplastic since they showed mild to moderate cell atypism. There were foci consisting of fibroblastic cells or osteoid and osteoblasts within the tumor. Those cells in the foci were apparently continuous with the surrounding stromal cells, and they were, therefore, also considered to be neoplastic. These findings strongly indicate that the stromal cells originate from the undifferentiated mesenchymal cells in the bone marrow and may differentiate to osteoblastic, fibroblastic, and histiocytic cells. All cells of these three series were not stained for a high stable form of acid phosphatase (SAPhase). SAPhase activity was demonstrated only in osteoclast-like giant cells and some mononuclear cells, which are recently believed to be non-neoplastic. Therefore, the cell atypia of SAPhase negative stromal cells is considered to have a prognostic value.     

The mechanism of metastasis in the so-called “benign giant cell tumor of bone”

A case of so-called “benign giant cell tumor of bone” with an incidental histologic finding of intratumor vascular invasion is reported. The mechanism and biology of metastasis are briefly discussed. For the purposes of this presentation, the mechanism of metastasis is divided into two types—active and passive. An active type of metastasis indicates malignancy, whereas a passive type denotes a benign process. The malignant features of the conventional or typical giant cell tumor of bone are demonstrated. It is proposed that this neoplasm be labeled malignant despite its seemingly benign histologic appearance. Relative to the degree of malignancy, a lesion of this nature may be classified as either a low or a high grade type of malignant giant cell tumor.     

Gene expression profiling identifies p63 as a diagnostic marker for giant cell tumor of the bone.

Giant cell tumor of the bone (GCTOB) is a primary bone tumor that occurs mainly in young adults and is capable of locally aggressive growth. Its histologic appearance can resemble a number of benign and malignant tumors but no useful diagnostic marker is known currently. To identify diagnostic markers for this tumor, global gene expression profiling using cDNA microarray was performed on 6 fresh-frozen GCTOB, 3 aneurysmal bone cysts, 4 fibrous dysplasias and 12 giant cell tumors of tendon sheath/diffuse-type giant cell tumors. Unsupervised hierarchical clustering separated the tumors based on their histopathologic types, and significance analysis of microarray identified several genes including TP73L (encoding the p63 protein) that are significantly highly expressed in GCTOB relative to these other tumors. The diagnostic utility of p63 was subsequently confirmed using anti-p63 antibody on a series of 26 GCTOB, 25 aneurysmal bone cysts, 15 chondroblastomas, 13 giant cell reparative granulomas, 13 chondromyxoid fibromas, 4 brown tumors, 4 fibrous dysplasias, 53 giant cell tumors of tendon sheath/diffuse-type giant cell tumors and 385 additional mesenchymal tumors in tissue microarrays. Strong p63 nuclear staining was present in 18 of 26 (69%) GCTOB, 3 of 15 (20%) chondroblastomas and in 1 of 25 (4%) aneurysmal bone cysts while none of the other tumors commonly considered in the differential diagnosis of GCTOB showed any detectable p63 staining. Strong p63 staining is rare in bone and soft-tissue tumors in general. In contrast to the pattern of p63 staining, the majority of the chondroblastomas (70%) demonstrated S-100 immunoreactivity while only a minority of the GCTOB (8%) was immunoreactive for S-100. These findings altogether show that p63 can be used as a diagnostic marker to aid the clinical diagnosis of GCTOB.     

Giant cell tumor of bone

Summary Eleven benign giant cell tumors of bone were studied in the electron microscope, and the fine structural localization of acid phosphatase was elucidated. Three distinct cell types are always present in these tumors: stromal cells type 1; stromal cells type 2; and multinucleated giant cells. Small mononuclear cells may also occur, but are not likely to be actively participating in the neoplastic process.The range of variability in the fine structure of the different cell types constituting this tumor has been established. Variations in appearances include: a) presence of nuclear pseudoinclusions in stromal cells type 1 and multinucleated giant cells; b) aberrations in the structure of the rough surfaced endoplasmic reticulum in the same cell types; c) occurrence of ruffled borders, ectoplasmic layers and cytoplasmic labyrinths containing acid phosphatase in the giant cells. Some giant cells show evidence of marked phagocytic activity and contain large and numerous residual bodies carrying acid phosphatase.The significance of the interrelations between the different cell types are discussed and the possible role of stromal cells type 2 in immunological mechanisms directed against the tumor cells are mentioned.This investigation has been aided by a grant from the Swedish Cancer Society (grant 77:64, project No. 617-B77-06XA)     

Expression of hepatocyte nuclear factor-1beta (HNF-1beta) in clear cell tumors and endometriosis of the ovary.

Clear cell tumors of the ovary are frequently associated with ovarian endometriosis. Clinicopathologically, it has been suggested that clear cell tumors develop from endometriosis, but there has been little molecular evidence supporting this speculation. Microarray analysis revealed recently that hepatocyte nuclear factor-1beta (HNF-1beta) was significantly upregulated in clear cell carcinoma of the ovary. In the present study, we examined 30 clear cell tumors (26 malignant, three borderline, and one benign) and 40 endometriotic cysts to clarify if differentiation into the clear cell lineage already begins in ovarian endometriosis. All of the 30 clear cell tumors, including borderline and benign ones, showed immunohistochemical expression of HNF-1beta in the nucleus, while other types of ovarian epithelial tumors (endometrioid, serous, mucinous, and Brenner tumors) rarely expressed it. Among 30 clear cell tumors, 17 (56%) cases were associated with endometriosis, and endometriotic epithelium was identified in 12 cases. In nine of the 12 cases, distinct nuclear immunostaining for HNF-1beta was detected in the endometriotic epithelium, as well as in the clear cell tumor. HNF-1beta expression was observed either in atypical endometriosis (four cases), or in endometriosis of a reactive nature (five cases). Furthermore, 16 of 40 (40%) endometriotic cysts without a neoplasm also expressed HNF-1beta, and the expression was almost exclusively observed in the epithelium showing inflammatory atypia. Our results indicate that HNF-1beta is an excellent molecular marker for ovarian clear cell tumors, including benign, borderline and malignant lesions. Early differentiation into the clear cell lineage takes place in ovarian endometriosis, not only in atypical endometriosis, but also in endometriosis with degenerative and regenerative changes, and this is probably responsible for the frequent occurrence of clear cell carcinoma in ovarian endometriosis.     

Fine-needle aspiration Is limited in the classification of benign breast diseases

Fine needle aspiration (FNA) has been proven to be accurate for the detection of breast carcinomas. However, its utility in the classification of benign breast lesions is less clear. We therefore undertook a study of 76 adequate preoperative FNAs of the breast from patients whose surgical biopsies of the breast were shown to be benign (18 nonproliferative diseases, 30 fibroadenomas, 19 proliferative breast diseases without atypia, and 9 proliferative breast diseases with atypia). A number of architectural and cellular features on cytology were evaluated. Histology slides were also reviewed. Both cytology and histology specimens were categorized as nonproliferative disease, fibroadenoma, proliferative breast disease without atypia, and proliferative breast disease with atypia. There was exact diagnostic correlation between cytology and histology in only 42 (55%) of the 76 cases. No cellular or architectural features on FNA examined correlated with the presence of epithelial proliferation on histology. The presence of two epithelial cell populations (one unremarkable and one atypical), small but prominent nucleoli, and nuclear pleomorphism on FNA significantly correlated with the presence of atypia on histology. However, these features are also present in breast lesions without proliferation or atypia, and are not diagnostic of atypical proliferative lesions of the breast. Therefore, FNA of the breast is limited in classifying benign breast diseases. Diagn. Cytopathol. 1998;18:56–61. © 1998 Wiley-Liss, Inc.     

Primary giant cell tumor of soft tissues similar to bone giant cell tumor: A case report and literature review

In this report we describe a primary giant cell tumor (GCT) of soft tissues located in the left dorsal wrist of a 52-year-old man. Plain radiographs did not reveal any lesion in his carpal or hand bones. Although the tumor was clinically considered a ganglion initially, the microscopic features were identical to those found in classic GCT of bone. Light microscopy showed a lesion composed of a homogeneously mixed proliferation of spindle and polygonal mononucleated stromal cells and evenly distributed multinucleated, osteoclast-like giant cells. Whereas most bone tumors have an extraosseous counterpart, only 13 cases of GCT in soft tissues had been published until 1998. Moreover, 64 new cases have been reported in three series. Nevertheless, most major reviews and textbooks do not consider this tumor as a specific entity and regard it as a low grade variant of malignant GCT of soft tissue. We describe the clinical, histologic, and immunohistochemical features of this rare benign neoplasm emphasizing the differential diagnosis with its malignant soft tissue counterpart, an ominous tumor.     

Fine-needle aspiration cytology of "ancient" schwannoma.

The term "ancient" schwannoma was proposed for a group of neural tumors showing degenerative changes and marked nuclear atypia. Prior to the realization that the observed atypia was a regressive phenomenon, many of these lesions were erroneously diagnosed as sarcomas. Fine-needle aspiration (FNA) cytologic material from five patients is included in this study. Tissue examined histologically included four resected tumors and 18 gauge core biopsies of one tumor. Aspirates of ancient schwannoma showed many of the same features as FNA of regular schwannoma: aggregates of spindled cells with indistinct cytoplasm and elongate nuclei with blunt point ends. The feature unique to these lesions was nuclear pleomorphism, which was identified in all aspirates. Nuclear inclusions were identified in all but one case. Cystic degeneration, xanthomatous changes, and perivascular sclerosis were identified in excised lesions. Ancient schwannomas show most of the FNA features of benign schwannomas but can demonstrate marked nuclear atypia. The FNA features of ancient schwannoma are important to note because of the potential to confuse this lesion with a more serious one such as sarcoma on FNA.     

Giant cell tumor of bone express p63.

p63 contributes to skeletal development and tumor formation; however, little is known regarding its activity in the context of bone and soft tissue neoplasms. The purpose of this study was to investigate p63 expression in giant cell tumor of bone and to determine whether it can be used to discriminate between other giant cell-rich tumors. Seventeen cases of giant cell tumor of bone were examined to determine the cell type expressing p63 and identify the isoforms present. Total RNA or cell protein was extracted from mononuclear- or giant cell-enriched fractions or intact giant cell tumor of bone and examined by RT-PCR or western blot, respectively. Immunohistochemistry was used to evaluate p63 expression in paraffin embedded sections of giant cell tumor of bone and in tumors containing multinucleated giant cells, including: giant cell tumor of tendon sheath, pigmented villonodular synovitis, aneurysmal bone cyst, chondroblastoma, and central giant cell granuloma. The mononuclear cell component in all cases of giant cell tumor of bone was found to express all forms of TAp63 (alpha, beta, and gamma), whereas only low levels of the TAp63 alpha and beta isoforms were detected in multinucleated cells; DeltaNp63 was not detected in these tumors. Western blot analysis identified p63 protein as being predominately localized to mononuclear cells compared to giant cells. This was confirmed by immunohistochemical staining of paraffin-embedded tumor sections, with expression identified in all cases of giant cell tumor of bone. Only a proportion of cases of aneurysmal bone cyst and chondroblastoma showed p63 immunoreactivity whereas it was not detected in central giant cell granuloma, giant cell tumor of tendon sheath, or pigmented villonodular synovitis. The differential expression of p63 in giant cell tumor of bone and central giant cell granuloma suggest that these two tumors may have a different pathogenesis. Moreover, p63 may be a useful biomarker to differentiate giant cell tumor of bone from central giant cell granuloma and other giant cell-rich tumors, such as giant cell tumor of tendon sheath and pigmented villonodular synovitis.     

Nerve sheath tumor with degenerative atypia and multivacuolated lipoblasts

Lipoblastic nerve sheath tumor is a recently described benign soft tissue tumor consisting of lipoblasts in a neural/schwannian background. The 6 reported cases have exclusively comprised signet ring lipoblasts and showed no cellular atypia. The authors describe the first lipoblastic nerve sheath tumor to harbor multivacuolated lipoblasts and degenerative atypia, underscoring its important differential diagnosis with well-differentiated liposarcoma. The purpose of this report is to expand the morphologic spectrum of this unusual neoplasm, and reemphasize the potential of benign nonadipocytic tumors to harbor multivacuolated lipoblasts and mimic liposarcoma.     

Diffuse pigmented villonodular synovitis of the temporomandibular joint diagnosed by fine-needle aspiration cytology

Diffuse pigmented villonodular synovitis is a rare tumor in the temporomandibular joint region. This article deals with a 32-yr-old male who suffered from pain and swelling in the right temporomandibular joint region associated with restricted mouth opening. Computed tomography showed a tumor lateral to the temporomandibular joint. Arthrography revealed a displaced temporomandibular joint disk. Fine-needle aspiration cytology showed characteristic cellular changes, including rounded or oval cells with abundant cytoplasm and intracytoplasmatic hemosiderin deposits and numerous multinucleated giant cells without nuclear atypia. A benign mesenchymal lesion suggestive for pigmented villonodular synovitis was diagnosed and later verified at histologic examination. Fine-needle aspiration cytology seems to be useful for this diagnosis.