Spindle cell and pleomorphic lipoma: an ultrastructural study

Cytogenetics of Spindle Cell/Pleomorphic Lipomas: Karyotyping and FISH Analysis of 31 Tumors

BACKGROUND

Spindle cell/pleomorphic lipomas are benign tumors. Here, we present our cytogenetic data on 31 such tumors.

MATERIALS AND METHODS

G-banding chromosome analysis and (in selected cases) fluorescence in situ hybridization (FISH) using probes for FOXO1, RB1, and HMGA2 were performed.

RESULTS

Rearrangements of chromosome 13 were found in 58% of tumors. Chromosomes 6, 1, 12, and 11 were also involved in 42%, 26%, 26%, and 23% of tumors, respectively. FISH analysis showed heterozygous deletion of RB1 in seven samples with chromosome 13 aberrations. In four of them, FOXO1 was also deleted. In two tumors with 12q15 rearrangements, FISH confirmed that HMGA2 was targeted.

CONCLUSION

Structural rearrangements of 13q or losses of an entire chromosome 13 are the most common cytogenetic aberrations in spindle cell/pleomorphic lipomas. However, cytogenetic variation exists similarly to what is found in other lipomas, suggesting that various pathways may be responsible for tumorigenesis.

Loss of retinoblastoma in pleomorphic fibroma: An immunohistochemical and genomic analysis

BACKGROUND

Pleomorphic fibroma is a curious neoplasm that exhibits striking cytologic atypia, yet behaves in benign fashion. The cytologic features include single cells with pleomorphic nuclei and scattered giant cells resembling the neoplastic cells of pleomorphic lipoma, a tumor with known retinoblastoma (Rb) loss.

METHODS

We assessed the demographic and histopathologic features of a cohort of 26 pleomorphic fibromas, including assessment with immunostaining for Rb, p16 and Ki-67. Array comparative genomic hybridization (aCGH) was used to assess a limited number of tumors for genomic aberrations.

RESULTS

Of the 26 pleomorphic fibromas analyzed, 19 occurred in women and 7 in men, with a mean age of 47 years. The anatomic locations were variable. Immunostaining showed loss of Rb protein expression in all cases and diffuse p16 expression in 85%. Ki-67 labeling rate was below 10% in 85%. Chromosome 13q loss was found in 7 of 7 pleomorphic fibromas assessed with aCGH. Recurrent loss of 17p, 16q and 10q were also found.

CONCLUSION

We report recurrent loss of RB1 on chromosome 13q in pleomorphic fibromas, confirmed by both protein expression loss and loss of 13q by aCGH. This result indicates pleomorphic fibroma shares the same genetic abnormalities as spindle cell and pleomorphic lipomas.

Solitary fibrous tumor of the oral cavity: clinicopathologic and immunohistochemical study of 21 cases

We describe clinical, morphologic, and immunohistochemical features of 21 cases of solitary fibrous tumor presenting in the oral cavity. There were 9 male and 12 female patients with a median age of 51 years (range 37-83). The most common locations included the buccal mucosa (the most common site), lip, maxillary or mandibular vestibule and tongue. Histopathologic examination showed well-circumscribed tumors with two well-defined patterns: the classic pattern with densely cellular areas alternating with hypocellular areas in a variably collagenous, vascular stroma and a more uniformly sclerotic pattern with only subtle classic areas. The spindle-shaped neoplastic cells consistently showed immunoreactivity for antibodies directed against CD34. Five of nineteen cases (26%) were reactive for CD99 and 19 of 19 for Bcl-2. Follow-up information was available in 17 cases and averaged 54 months, with no evidence of recurrence or metastasis in any of these patients. Awareness that solitary fibrous tumor may present in the oral cavity is important so that confusion with other spindle cell neoplasms can be avoided. We also briefly describe the differential diagnosis and compare this series, the largest single series of intraoral SFT, to cases previously reported in the literature.

Infiltrating intramuscular spindle cell lipoma of the face

Spindle cell lipoma is a benign lipomatous tumor, which usually arises on the back of the neck, shoulder or upper back of males in the third to seventh decade of life. We report herein an unusual infiltrating intramuscular spindle cell lipoma arising in the nose of a 53-year-old man. The patient presented with a 0.5-cm 'cyst' of the nose, just above the right alar crease, which was removed. Four years later, the lesion recurred and was re-excised. Histologically, a proliferation of mature adipocytes, ropey collagen fibers and spindle cells within a myxoid stroma was present in the subcutaneous tissue and infiltrated between skeletal muscle fibers. Nine cases of intramuscular spindle cell lipoma with histological examination have previously been reported and have involved the oral cavity and muscles of the extremities. To our knowledge, this is the first report of an infiltrating intramuscular spindle cell lipoma arising on the face.

Floretlike Cells in In Situ and Prolapsed Orbital Fat

PURPOSE

Orbital pleomorphic lipoma has been rarely reported in the literature. Although floretlike cells are characteristic of pleomorphic lipoma, they are not pathognomonic. We reviewed cases of prolapsed orbital fat and exenteration specimens to determine the significance of presence of these cells in the diagnosis of orbital pleomorphic lipoma.

DESIGN

Retrospective interventional case series with clinicopathologic correlation.

PARTICIPANTS

Seventy-two specimens of 45 patients with prolapsed orbital fat and 74 exenteration specimens as controls.

INTERVENTION

Histologic review of the specimens including light microscopy, Masson trichrome staining, immunostaining for S100, CD34, CD68, terminal deoxynucleotidyl transferase-mediated dUTP nick end-labeling (TUNEL) assay, and transmission electron microscopy and review of clinical records and analysis of the data with generalized estimation equation.

MAIN OUTCOME MEASURE

Evidence of histologic abnormalities in histologic specimens and clinical and demographic data.

RESULTS

Floretlike cells were present in 31 of 72 (43%) specimens of prolapsed orbital fat and in 12 of 74 (16%) orbital exenterations. Fewer than 6 florets were present in twenty 40x high-power fields in 15 (48%), 6 to 10 in 9 (29%), and >10 in 7 (23%) specimens. The florets stained positive for CD34 but not for S100 or CD68. TUNEL assay revealed significant nuclear pyknosis, and transmission electron microscopy disclosed spindle-shaped cells with abundant rough endoplasmic reticulum and no basement membrane. The mean age of patients with prolapsed orbital fat with florets was 67 years (range, 52-86). Of 31 samples, 29 (94%) were from males. Of 30 samples, 29 (97%) were located in the superotemporal conjunctiva; only one was located in the lower lid. There was significant association between the presence of florets and location of the prolapsed orbital fat (P = 0.0013) and gender (P = 0.0015).

CONCLUSION

Floretlike cells may be present in in situ and prolapsed orbital fat as a degenerative process. What some have called "orbital pleomorphic lipoma" is in fact only age-related orbital fat prolapse.

Angiomatous spindle cell lipoma: Report of three cases with immunohistochemical and ultrastructural study and reappraisal of former 'pseudoangiomatous' variant

Pseudoangiomatous spindle cell lipoma (PASCL) is a rare variant of spindle cell lipoma that is composed of spindle fibroblast-like cells and mature adipose cells, and that is further characterized by intratumoral branching spaces regarded originally to be non-vascular (hence the adjective 'pseudoangiomatous'). Reported herein are three cases of this tumor, with literature review of all six cases described previously. PASCL appears to have clinical features (age, sex, location, prognosis) similar to those of conventional spindle cell lipoma (SCL). Immunohistochemically, the spindle cells in all of the present cases were positive for CD34, as in conventional SCL. All lesions had at least mild positivity for sex steroid hormone receptors. The cells lining intratumoral dilated and branching spaces typical of this variant were strongly positive for lymphatic endothelial marker D2-40 in all cases, and for vascular markers CD31 and F-VIII in one case. Ultrastructural study confirmed the endothelial nature of these cells. The results indicate that pseudoangiomatous SCL is truly angiomatous and should be termed as such. It could represent a sex steroid hormone-dependent lesion.

Spindle cell lipoma of the floor of the mouth: Report of a case

Spindle cell lipoma is a benign tumour composed by: (1) mature fat cells; (2) spindle cells; (3) a myxoid matrix separated by thick bands of birefringent collagen. Only 14 cases have been reported in the oral cavity. The authors present the second case located in the floor of the mouth. The treatment of the lesion consists of a local excision.

Mast cells: the forgotten cells of renal fibrosis

BACKGROUND/AIMS

Mast cells, when activated, secrete a large number of fibrogenic factors and have been implicated in the development of fibrotic conditions of the liver, lung, and skin. There is evidence that renal fibrosis is closely linked with a chronic inflammatory cell infiltrate within the interstitium, but a potential role for mast cells in this process has yet to be defined. Therefore, the numbers of mast cells in normal and fibrotic kidneys with various pathologies were investigated.

METHODS

Mast cells were quantified in renal transplants showing acute and chronic rejection and cyclosporin toxicity, kidneys removed for chronic pyelonephritis, and renal biopsies from patients with IgA nephropathy, membranous nephropathy, and diabetic nephropathy. Mast cells were stained using two methods: acid toluidine blue detected less than 30% of the mast cells revealed by immunohistochemistry for mast cell tryptase.

RESULTS

Mast cells were scarce or absent in normal kidney (median, 1.6 mast cells/mm2) but numerous throughout the cortex and medulla in all specimens that showed fibrosis. They were almost entirely confined to the renal interstitium. Mast cells were present in large numbers in biopsies from patients with membranous nephropathy (median, 21.7 mast cells/mm2) and diabetic nephropathy (median, 29.2 mast cells/mm2), which were selected on the basis of showing chronic injury. In 24 unselected IgA nephropathy biopsies there was a close correlation between numbers of mast cells and the extent of interstitial fibrosis (r = 0.771; p < 0.0001). In renal transplant biopsies, mast cells were associated with allograft fibrosis in chronic rejection (median, 27.1 mast cells/mm2) and chronic cyclosporin toxicity (median, 10.6 mast cells/mm2) but not acute rejection (median, 2.7 mast cells/mm2) or acute cyclosporin toxicity (median, 2.0 mast cells/mm2). There was no detectable increase in mast cell numbers during acute rejection in those transplants that subsequently progressed to chronic rejection. In some biopsies the mast cells were largely intact, but in most cases some or all were degranulated.

CONCLUSIONS

An increased number of mast cells is a consistent feature of renal fibrosis, whatever the underlying pathology, and the number of mast cells correlates with the extent of interstitial fibrosis. This suggests that mast cells might play a pathogenetic role in the fibrotic process.

Spindle-cell lipoma of the cheek: a case report

Spindle-cell lipoma (SCL) is a distinct histological variant of lipoma. Clinically, it appears as a solitary, subcutaneous, circumscribed lesion. SCL accounts for about 1.5% of all adipocytic tumours. Only nine cases of intraoral SCL were found in the literature. Microscopically, mature adipocytes and spindle cells are immersed in a myxoid stroma. SCL needs only local excision, and it does not recur.

Pleomorphic lipoma: case report and literature review

BACKGROUND

Pleomorphic lipoma is a rare, benign, pseudosarcomatous, soft tissue neoplasm typically involving the subcutis of the neck and shoulder in middle-aged to elderly men. It is characterized histologically by atypical, multinucleated giant cells and grossly as a well-circumscribed mass. Since this neoplasm can resemble a sarcoma, histopathologic diagnosis is critical in preventing unnecessary surgery.

OBJECTIVE

To describe a case of pleomorphic lipoma in the neck and to review the clinical and histopathologic characteristics of this neoplasm.

METHODS

We present a case report and review of the literature.

RESULTS

Local excision to completely extirpate this neoplasm has proven curative at 10 months of follow-up.

CONCLUSION

Pleomorphic lipoma is superficially located and may be encountered in a dermatologic setting. Thus the dermatologist should become familiar with its clinical presentation and microscopic appearance.

Multiple spindle cell lipomas: a report of 7 familial and 11 nonfamilial cases

Spindle cell lipoma, a variant of a benign lipoma, usually occurs as a solitary, subcutaneous, circumscribed lesion in the posterior back, neck, or shoulders of older men. Multiple lesions are exceedingly rare. To our knowledge, there have been no previous series reported of patients with multiple subcutaneous spindle cell lipomas. We examine the clinicopathologic findings of a group of patients with multiple spindle cell lipomas, including seven with a familial occurrence of this disease. The Soft Tissue Registry of the Armed Forces Institute of Pathology and the consultation files of one of the authors (S.W.W.) from the Department of Pathology at the University of Michigan were searched for patients with multiple spindle cell lipomas. All patients' records, clinical history, and pathology were reviewed. All patients had a minimum of two tumors that met strict morphologic criteria for spindle cell lipoma. Pleomorphic cells, typical of pleomorphic lipoma, were observed in some cases and were acceptable as part of the spectrum of spindle cell lipomas. Associated lesions, family history, ethnic background, daily habits, and natural progression of disease were recorded and compared. Eighteen patients in our files met the criteria for multiple spindle cell lipomas; 4 of the 18 patients were from the same family. Three additional patients had a family history of multiple spindle cell lipomas. The ratio of patients with multiple spindle cell lipomas to all patients with spindle cell lipoma in the two consultation files was 0.5 and 3%, respectively. All of the patients in our study were male; three had a family history of females with less severe disease (fewer and smaller spindle cell lipomas); however, no material from these female patients was available for review. All but four patients presented in their sixth through eighth decades of life; yet, several older patients stated that their first lesion occurred in their fifth decade. Patients had between 2 and >220 lesions, which usually commenced on the posterior neck or back, commonly followed by additional bilateral lesions on the shoulders and upper torso. The natural history of this disease revealed development of multicentric lesions over several years, for both familial and nonfamilial cases. The tumors became more cellular as the disease progressed, often with features of pleomorphic lipoma; however, no patients developed spindle cell liposarcoma. Multiple spindle cell lipomas are rare. The clinical presentation may mimic Madelung's disease (symmetrical lipomatosis). As mentioned above, some cases are familial. Genetic predisposition must be further examined. There appears to be no common ethnic background, environmental exposure, medical condition, or syndrome of associated lesions with multiple spindle cell lipomas.

Angiomyofibroblastomalike tumor of the male genital tract: analysis of 11 cases with comparison to female angiomyofibroblastoma and spindle cell lipoma

The clinicopathologic features and immunoprofile of 11 cases of an uncharacterized male genital tract tumor with features of vulvovaginal angiomyofibroblastoma (AMF) and spindle cell lipoma (male AMF-like tumor) are described. The lesions presented as a mass involving the scrotum (six cases) or inguinal region (five cases) in males ranging in age from 39 to 88 years (median 57). The tumors were superficially located and well-marginated and ranged in size from 2.5 to 14 cm (approximate mean 7 cm). Microscopically, they were composed of tapered spindled cells proliferating between numerous small to medium-sized vessels. Epithelioid appearing stromal cells were a focal finding in four cases. Mitotic activity was minimal with no abnormal mitotic figures identified. Mild nuclear atypia was identified in two cases. The tumors possessed an acid mucopolysaccharide-rich, finely collagenous stroma. A small quantity of intralesional fat was present in six cases. Tumor cells exhibited immunoreactivity for vimentin (seven of seven cases), progesterone receptor protein (five of seven cases), CD34 (four of eight cases), estrogen receptor protein (three of seven cases), desmin (three of eight cases), muscle-specific actin (three of eight cases), and smooth-muscle actin (two of eight cases) but not for S-100 protein. One of seven patients with follow-up after simple excision had recurrent/persistent disease. The male AMF-like tumor is a soft-tissue neoplasm of the male genital tract that shares clinicopathologic features and a proposed perivascular stem cell derivation with both the female angiomyofibroblastoma and spindle cell lipoma.

Fibrohistiocytic differentiation in subcutaneous fatty tumors. Study of spindle cell, pleomorphic, myxoid, and atypical lipoma and dedifferentiated liposarcoma cases composed in part of CD34+ fibroblasts and FXIIIa+ histiocytes

Subsets of dendritic cells, fibroblasts which express the human progenitor cell antigen CD34 or histiocytes which express coagulation factor XIIIa (FXIIIa), are present in fat and in collagenous connective tissue. As components of the microvascular unit, these fibrohistiocytic cell subsets may interact during stromal remodeling, repair, and neoplasia. We studied white fat and subcutaneous fatty tumors to determine if CD34 and/or FXIIIa+ "fibrohistiocytic" dendritic cell subsets are involved in their morphogenesis. Three lipomas (L), 1 intramuscular lipoma (IL), 1 myxoid lipoma (ML), 2 pleomorphic lipomas (PL), 2 spindle cell lipomas (SCL), 8 angiolipomas (AN) in 4 patients, 1 atypical lipoma/well-differentiated liposarcoma (AL), 1 de novo dedifferentiated liposarcoma (DL), and 1 recurring atypical myxoid signet ring lipomatous tumor were examined for CD34, FXIIIa and in some cases for CD31, desmin, Ki 67, or S-100. Normal fat has scattered CD34+ dendritic cells and small FXIIIa+ dendritic histiocytes among variably S-100+ adipocytes. The CD34 and FXIIIa+ dendritic cells are more numerous near vessels and within fibrovascular septae. In L and IL, CD34 and FXIIIa+ dendritic cells are activated and some adipocytes express CD34. Mesenchymal areas of SCL, PL, ML, and AL and DL are composed of CD34+ dendritic cells with CD34+ but FXIIIa-negative floret cells in PL or atypical cells in AL and DL. FXIIIa+ dendritic cells are numerous in these lesions, comprising 30-40% of cells in SCL and PL, and 50% in ML, AL, and DL. AN have focal CD34+ interstitial cells and plump FXIIIa+ cells that in one case resembled multivacuolated lipoblasts. The myxoid signet ring lipomatous tumor was CD34 negative with few FXIIIa+ cells. We conclude that subsets of CD34+ and FXIIIa+ dendritic microvascular cells are present in normal fat and proliferate together in various types of lipomas and in at least some dedifferentiated liposarcomas.

Pleomorphic hyalinizing angiectatic tumor of soft parts: immunohistochemical case study shows cellular composition by CD34+ fibroblasts and factor XIIIa+ dendrophages

We report immunomorphologic observations on a pleomorphic hyalinizing angiectatic tumor of soft parts (PHAT), a rare tumor recently described by Smith, Fisher, and Weiss. A 2 cm skin-covered, grossly lobulated, firm, yellow-tan, focally hemorrhagic tumor was excised from the dorsum of a 59-year-old woman's right foot. It infiltrated dermis and subcutis and entrapped skin adnexae. The tumor microscopically resembled both a pleomorphic malignant fibrous histiocytoma and a neurilemoma with fascicular spindle cell pattern, pleomorphic tumor giant cells, and focal congeries of ectatic, fibrinous, and slightly hyalinized vessels. Tumour cells produced abundant reticulin but collagenous sclerosis was minimal. Mast cells were numerous. Pleomorphic cells, some phagocytic, had intranuclear vacuolar inclusions and many cells had large pale cytoplasmic globular inclusions. Most tumor cells expressed vimentin and CD34, including pleomorphic cells. Factor XIIIa stained focally 20-40% of the spindle cells. S-100 and cytokeratin were negative and actin and desmin stained only vessel myopericytes. The Ki 67 index was 3% with mostly large CD34+ cells and a few smaller FXIIIa+ cells in the cycling fraction. We conclude that PHAT is a fibrohistiocytic tumor probably derived from proliferating microvascular CD34+ dendritic cells and FXIIIa+ dendrophage cell subsets. Possible interactions between these cell types deserve further study in PHAT and other fibrohistiocytic tumors.

Mast cell interaction with tumor cells in small early gastric cancer: ultrastructural observations

The authors studied the mast cells by light and electron microscopy in four small intramucosal early gastric cancers (EGC). Mast cells were found in the tumor stroma and among neoplastic cells of adenocarcinoma glands. Stromal and adenocarcinoma-infiltrating mast cells were ultrastructurally identified as T mast cells, and exhibited anaphylactic or piecemeal degranulation. Tumor cells in intimate contact with mast cells showed no cytopathic changes. These data do not support a mast cell-mediated cancer lysis, such as that reported in some systems in vitro. The interepithelial localization of T mast cell in adenocarcinoma glands is similar to that observed in some disease states, including interstitial cystitis, fibrotic lung disorders, and mucosal allergic reaction. The findings suggest that T mast cells may be involved in the pathophysiology of the host reaction to small intramucosal EGC.