An atypical lipomatous tumor mimicking a giant fibrovascular polyp of the hypopharynx: A case report

RATIONALE

Giant fibrovascular polyps (GFVPs) found in the hypopharynx are exceedingly rare. These are benign tumors which are identified by CT or MRI and usually treated based on symptoms. Even more rarely, pathology may identify one of these masses as an atypical lipomatous tumor (ALT). This paper will present a case of an ALT of the hypopharynx that was originally classified as a GFVP, highlighting the difficulty in distinguishing between them and the importance of making the correct diagnosis.

PATIENT CONCERNS

An 84-year-old man presented to the emergency department with a 6-month history of a pedunculated hypopharyngeal growth, dysphagia, and intermittent dyspnea.

DIAGNOSES

The mass was characterized as a GFVP by barium swallow and MRI.

INTERVENTIONS

The hypopharyngeal mass was resected for obstructive symptoms and to confirm the diagnosis. Final pathology found the mass to be more consistent with an atypical lipomatous tumor (ALT).

OUTCOMES

The patient's dysphagia and dyspnea resolved. He was free of recurrence at 22 months postoperative.

LESSONS

Both GFVPs and ALTs are very rarely found in the hypopharynx but can be easily misclassified as one another. Imaging is useful to initially characterize the mass, but to definitively differentiate between them, pathological analysis is necessary. Although they are rare, it is important to consider both possibilities on the differential for hypopharyngeal masses. Further, accurate analysis is essential to distinguish between them because their definitive management and follow-up is different.

Lipomatous tumours in adrenal gland: WHO updates and clinical implications

Adrenal lipomatous tumour is a group of adrenal tumours with a significant component of adipose tissue. According to the current World Health Organization (WHO) classification of tumours of endocrine organs, adrenal myelolipoma is the only entity amongst the group of tumours being described. In the literature, other more recently documented adrenal lipomatous tumours included 24 lipomas, 32 teratomas and 16 angiomyolipomas. Rare fatty tumours of the adrenal gland comprised liposarcoma, hibernoma, adrenocortical tumours with fat component and rare adrenal tumours with fat component. Myelolipoma comprises approximately 3% of primary adrenal tumour. It is noted more commonly in females and in the right adrenal gland. Approximately 40 bilateral myelolipomas were reported. The tumour is most frequently recorded in patients between fifth and seventh decades of life. Adrenal lipomas are often seen in males and in the right adrenal gland. They were commonly noted in patients in the sixth decade of life. The diagnosis could only be possible on examination of the surgically removed specimen. Adrenal teratomas were more common in females and with a bimodal age distribution. Slightly over 60% of the patients with adrenal teratoma are symptomatic. Adrenal angiomyolipomas were often symptomatic, more common in females and in the fifth decades of life. To conclude, adrenal lipomatous tumour is uncommon. They are often benign and non-functional. It is important to recognize the features of this group of lipomatous tumours in the adrenal gland as they are being detected on increasing incidence as a result of the wide-spread use of modern imaging modalities.

[Clinical classification and surgical management of cervicothoracic intraspinal lipomas]

OBJECTIVE

To explore the clinical classification and surgical management of cervicothoracic intraspinal lipomas.

METHODS

A total of 22 patients with cervicothoracic intraspinal lipomas were analyzed retrospectively with regards to clinical manifestations, radiographic features, intraoperative findings, surgical techniques and follow-ups.

RESULTS

Total (n = 4), subtotal (n = 7) and partial (n = 11) resection was performed. Long-term neurological outcomes were evaluated by modified McCormick classification scheme. Their symptoms improved (n = 15), unchanged (n = 3) and deteriorated (n = 4). And cervicothoracic intraspinal lipomas could be classified into extradural, transitional, chaotic and secondary intramedullary groups.

CONCLUSION

Different groups of cervicothoracic intraspinal lipomas vary in the degree of resection and surgical efficacy. Total resection may be performed on most extradural lipomas. The surgical objective of transitional lipomas is decompression. Chaotic and secondary intramedullary lipomas should target effective resection to avoid neurological function injury. Intraoperative use of laser facilitates tumor resection. Intraoperative electrophysiological monitoring protects spinal cord.

Sialolipoma of a minor salivary gland in a dog

A 10-year-old golden retriever dog was presented for evaluation of progressive panting, inspiratory stridor, and gagging. Oropharyngeal examination revealed a soft, nonulcerated, pedunculated mass arising from the right tonsillar fossa. The mass was completely excised and histopathology was consistent with a sialolipoma. No regrowth of the mass was evident 6 months after surgery.

CLASSIFICATION OF BENIGN FATTY TUMOURS OF THE UPPER LIMB

In this paper, the authors offer a classification of benign fatty tumours of the upper limb. There are three histologically distinct types of fat cells: immature fat cells which give rise to lipoblastomas, mature brown fat cells which give rise to hibernomas and mature white fat cells which give rise to lipomas. Lipomas are the most common and they are sub-classified according to the anatomic site of fat cells into dermal, subcutaneous and sub-fascial lipomas; or tumours directly related to muscle, bone, synovium or nerve. Finally, the authors review 67 patients with benign fatty tumours of the upper limb and provide clinical examples of these tumours including their characteristic histological and radiological features.

Benign fatty tumors: classification, clinical course, imaging appearance, and treatment

Lipoma is the most common soft-tissue tumor, with a wide spectrum of clinical presentations and imaging appearances. Several subtypes are described, ranging from lesions entirely composed of mature adipose tissue to tumors intimately associated with nonadipose tissue, to those composed of brown fat. The imaging appearance of these fatty masses is frequently sufficiently characteristic to allow a specific diagnosis. However, in other cases, although a specific diagnosis is not achievable, a meaningful limited differential diagnosis can be established. The purpose of this manuscript is to review the spectrum of benign fatty tumors highlighting the current classification system, clinical presentation and behavior, spectrum of imaging appearances, and treatment. The imaging review emphasizes computed tomography (CT) scanning and magnetic resonance (MR) imaging, differentiating radiologic features.

Epilepsy in patients with spina bifida in the lumbosacral region

This study aimed to assess the relevance of epilepsy and spina bifida in the lumbosacral region. We evaluated 75 patients with spina bifida admitted to the Kyushu University Hospital from 1980 to 2004. Patients were classified as having meningocele (MC, 4 cases), myelomeningocele (MMC, 6), myeloschisis (MS, 45), and lumbosacral lipoma (LL, 20). Nine cases had epileptic disorders, and all showed MS. Meticulous neuroradiological investigations revealed cerebral abnormalities such as polymicrogyria or hypogenesis of the corpus callosum in all epileptic cases. Locations of cerebral abnormalities topographically correlated with areas of interictal EEG abnormalities. Although all epileptic cases had ventriculoperitoneal (VP) shunt for hydrocephalus before the onset of epilepsy, interictal EEG abnormalities could not be explained by location of the VP shunt. In all LL patients, neither history of epilepsy nor cerebral abnormalities were noted on magnetic resonance imaging (MRI). Epileptogenesis in spina bifida patients seemed to correlate with coexisting cerebral abnormalities in MS patients rather than with the VP shunt. However, not all spina bifida patients associated with cerebral abnormalities had epilepsy, and not all cerebral abnormalities were epileptogenic, suggesting that epilepsy in spina bifida patients was multifactorial.

Sialolipoma of the parotid gland

A case of slow-enlarging mass of the parotid region in a 44-year-old male is presented, which proved to be a lipomatous tumour of the parotid gland. The clinical impression was that of a benign salivary gland tumour. The tumour was situated in the deep lobe of the gland, thus a total parotidectomy was performed, with preservation of the facial nerve. Microscopically the lesion was described as consisting of mature adipose tissue, which, however, encompassed both glandular elements and nerve bundles within it. This tumour has been recently recognized as a separate entity under the term 'sialolipoma'.

Lipoma of the oral and maxillofacial region: Site and subclassification of 125 cases

OBJECTIVE

Lipomas and lipoma variants are common soft tissue tumors, but occur infrequently in the oral and maxillofacial region. In this study, we reviewed 125 lipomas in specific oral and maxillofacial locations. We wanted to examine and compare the clinicopathologic features of these tumors. Study design The records from the Oral and Maxillofacial Pathology Registry of the Armed Forces Institute of Pathology from 1970 to the present were searched for cases coded as "lipoma." This study included 125 cases based on location within the oral and maxillofacial region, benign histology, and available clinical information. Subcutaneous and intraosseous lipomas were excluded. The tumors were classified according to the most recent World Heath Organization classification for soft tissue tumors.

RESULTS

Of 125 lipomas, 91 tumors occurred in males, 33 in female patients, and 1 of unknown gender. The mean age was 51.9 years, range 9-92 years. Four tumors occurred in pediatric patients (age <18 years). Specific anatomic sites within the oral and maxillofacial region included the parotid region (n=30); buccal mucosa (n=29); lip (n=21); submandibular region (n=17); tongue (n=15); palate (n=6); floor of mouth (n=5); and vestibule (n=2). The mean size of tumors was 2.2 centimeters, range 0.5 to 8.0 centimeters. The mean duration of the tumors prior to excision was 3.2 years, range 6 weeks to 15 years. Most patients presented with an asymptomatic, circumscribed mass. Grossly, most tumors were described as pink and smooth, occasionally mucoid. Histologically, the tumors were subclassified as classic lipomas (n=62); spindle cell/pleomorphic lipomas (n=59); fibrolipoma (n=2), and chondroid lipoma (n=2). Fourteen tumors exhibited secondary changes, such as fat necrosis, atrophy, and prominent hyalinization; 23 tumors were histologically confirmed to be intramuscular.

CONCLUSIONS

Lipomas of the oral and maxillofacial region occur most commonly in adult males in the parotid region, followed closely by the buccal mucosa. These tumors are uncommon in children. Interestingly, spindle cell lipomas are common in this region and comprise the majority of our parotid and lip tumors. Angiolipomas were absent in this anatomic region in this study. Secondary changes and atrophy should not be confused with the malignant histologic features of a liposarcoma.

Genetic and expression profiles of cerebellar liponeurocytomas

Cerebellar liponeurocytoma, a rare, newly identified CNS neoplasm of adults, is characterized by advanced neuronal/neurocytic and focal lipomatous differentiation, low proliferative potential and a favorable clinical prognosis. Despite the different age distribution and benign biological behavior, the cerebellar liponeurocytoma shares several features with the cerebellar medulloblastoma, which may include an origin from the periventricular matrix of the fourth ventricle or the external granular layer of the cerebellum. To establish the genetic profile of cerebellar liponeurocytomas, we have formed an international consortium and collected tumor samples from 20 patients. DNA sequencing revealed TP53 missense mutations in 4 (20%) of 20 cerebellar liponeurocytomas, a frequency higher than in medulloblastomas. There was no case with PTCH, APC, or beta-catenin mutations, each of which may be present in subsets of medulloblastomas. Isochromosome 17q, a genetic hallmark of classic medulloblastomas, was not observed in any of the cases investigated by FISH analysis. cDNA array analyses were carried out on 4 cerebellar liponeurocytomas, 4 central neurocytomas, and 4 classic medulloblastomas. Cluster analysis of the cDNA expression data of 1176 genes grouped cerebellar liponeurocytomas close to central neurocytomas, but distinct from medulloblastomas. These results suggest cerebellar liponeurocytoma as a distinct tumor entity that is genetically different from medulloblastoma. Furthermore, the cDNA expression array data suggest a relationship to central neurocytomas, but the presence of TP53 mutations, which are absent in central neurocytomas, suggests that their genetic pathways are different.

Lipomatous tumors of soft tissue: MR appearance with histological correlation

There is a broad spectrum of lipomatous tumors that involve soft tissues including ordinary lipomas, variants of lipomas, heterotopic lipomas, lipomatosis, hibernomas and liposarcomas. The recognition of these tumors is important to avoid diagnostic pitfalls. The MR imaging appearance of the lesion, including location, shape and internal architecture, suggests the diagnosis of lipomatous tumors. The signal intensity on T1-, T2-, fat-suppressed T2-weighted (FS-T2) images or short tau inversion recovery (STIR), T1- and fat-suppressed T1-weighted images after Gd-DTPA administration can be a useful aid in distinguishing between biologically different types of lipomatous tumors. The imaging features are often characteristic and reflect the histological pattern of the tumors. We present an overview of the lipomatous tumors and we correlate MR imaging appearance with histological findings.

Dynamic MRI and fine needle aspiration cytology in the evaluation of soft tissue lesions

OBJECTIVE

To assess the usefulness of dynamic magnetic resonance imaging (DMRI) in the diagnosis of soft tissue tumors.

DESIGN AND PATIENTS

A DMRI series of 33 patients with soft tissue lesions was evaluated with regard to start, pattern, and progression of enhancement. Early enhancement, predominantly peripheral, and a time-signal intensity (TSI) curve characterized by a steep rise to an early peak followed by a plateau or washout, were considered signs of malignancy. The results were compared with the initial fine needle aspiration cytology (FNAC) diagnosis and the final diagnosis.

RESULTS

Twenty of 23 malignant lesions and three of 10 benign lesions exhibited at least two of the three enhancement characteristics attributed to malignancy. Using two or more DMRI features of malignancy to dichotomize the series, the sensitivity and positive predictive value of the DMRI series were 87% and, the specificity and negative predictive value were 70%. FNAC was conclusive except in two cases.

CONCLUSION

In tumor centers that rely on FNAC for preoperative diagnosis DMRI can be reserved for cytologically inconclusive cases. In centers that rely on open biopsy, DMRI may be useful as a coarse discriminator between benign and malignant lesions. However, larger series of soft tissue tumors need to be evaluated to conclusively identify the clinical role of DMRI.

Cytomorphology of lipomatous tumors of soft tissue

OBJECTIVE

To evaluate the cytomorphologic features of benign and malignant lipomatous tumors of soft tissue on fine needle aspirates (FNA) and determine if the variants of liposarcoma could be identified.

STUDY DESIGN

FNA of histologically documented benign (51 cases) and malignant (39 cases) lipomatous tumors were reviewed. Twenty-six of the 51 FNA from lipomas and 34 of the 39 FNA from malignant lipomatous tumors were satisfactory for evaluation.

RESULTS

FNA from 26 cases of lipomas were cellular, with lobulated, fibroadipose tissue. Thin and thick capillaries were seen in 92% and 65% of cases, though a chicken wire vascular pattern was seen in only 4 cases (15%). A cytodiagnosis of liposarcoma could be made in 23 cases (88%), and these could be further subtyped into well-differentiated (4 cases), myxoid (8), pleomorphic (4), round cell (3) and liposarcoma, ?type (4). Only 50% of the well-differentiated liposarcomas, 3 of the 10 pleomorphic liposarcomas and 8 of the 17 myxoid liposarcomas were diagnosed as such on FNA. Cytologic diagnosis of the remaining 9 cases of myxoid liposarcoma were pleomorphic liposarcoma (1); liposarcoma, ?type (3); malignant mesenchymal tumor (1); suspicious for malignancy (2); and benign (2). There were no false positives, but there were 3 false negative cases (1 well-differentiated and 2 myxoid liposarcoma).

CONCLUSION

Lipomas can be diagnosed readily. Arborizing vessels can be seen in lipomas and should be interpreted with caution. Subclassification of liposarcomas on FNA is possible but not very reliable. Myxoid liposarcomas pose a problem, and aspirates from them can mimic a wide range of morphologic subtypes. The role of FNA in identification of variants of liposarcoma is limited.

Encapsulated versus nonencapsulated superficial fatty masses: a proposed MR imaging classification

OBJECTIVE

The purpose of this study was to assess the MR imaging appearance of palpable fatty masses and to propose terminology for palpable subcutaneous fatty masses that are nonencapsulated on MR imaging.

MATERIALS AND METHODS

We searched the past 7 years of our institution's radiology database for reports of MR images containing the word "lipoma." Medical records were reviewed to identify patients with palpable masses corresponding to fat. Two radiologists retrospectively reviewed the MR images for the presence of an encapsulated or nonencapsulated fatty mass in the region of the palpable abnormality. Pathologic specimens, when available, were also reviewed.

RESULTS

Between 1995 and 2001, 184 palpable subcutaneous fatty masses were evaluated on MR imaging. Of these, 46% (85/184) were encapsulated lipomas and 54% (99/184) were nonencapsulated fatty masses on MR imaging. Four masses (three encapsulated and one nonencapsulated) were surgically resected and had pathology consistent with lipomas.

CONCLUSION

Many palpable fatty masses do not have definable capsules on MR imaging. We propose that a palpable mass that corresponds to a nonencapsulated prominence of subcutaneous fat on MR imaging should be reported as a nonencapsulated lipoma. More definitive reporting of this relatively common lesion will assure the referring clinician of the benign nature.

Clustering of deletions on chromosome 13 in benign and low-malignant lipomatous tumors

Deletions and structural rearrangements of the long arm of chromosome 13 are frequently observed in benign and low-malignant lipomatous tumors, but nothing is known about their molecular genetic consequences. We assessed the karyotypes of 40 new and 22 previously published cases (35 ordinary lipomas, 15 spindle cell/pleomorphic lipomas, 2 myxolipomas, 1 angiomyxolipoma and 9 atypical lipomatous tumors) with chromosome 13-abnormalities, and found bands 13q12-22 to be frequently affected. Twenty-seven cases with structural abnormalities within this region were selected for breakpoint and deletion mapping by metaphase fluorescence in situ hybridization (FISH), using a set of 20 probes. Deletions were found in 23 of 27 cases. The remaining 4 cases had seemingly balanced rearrangements. The breakpoints were scattered but clustered to band 13q14, and in all cases with unbalanced abnormalities, a limited region within band 13q14 was partially or completely deleted. A deletion within band 13q14 was found together with a breakpoint on the other homologue in 5 cases, 4 of which could be tested further with regard to the status of the retinoblastoma (RB1)-gene. In all 4 cases, only 1 copy of the gene was deleted. In addition to the breaks and deletions in the vicinity of the RB1-locus, several other regions of 13q were recurrently affected, e.g., in the vicinity of the hereditary breast cancer (BRCA2; 13q12)- and lipoma HMGIC fusion partner (LHFP; 13q13)- genes. Our findings strongly indicate that deletion of a limited region (approximately 2.5 Mbp) within 13q14, distal to the RB1-locus, is of importance in the development of a subset of lipomatous tumors.

Lipomas of the oral cavity: clinical findings, histological classification and proliferative activity of 46 cases

Lipomas represent about 1 to 5% of all neoplasms of the oral cavity. Although relatively common, few large series of intraoral lipomas and its variants are seen in the literature. Therefore, the authors present the clinical, histological and immunohistochemical features of 46 cases of intraoral lipomas reviewed from the files of the University of Campinas Dental School from 1970 to 2001. Most of the cases affected adults, without gender predilection, and the main involved sites were the buccal mucosa (21 cases), tongue (six cases), lips (six cases) and floor of mouth (five cases). The histological analysis revealed 21 cases of lipoma, 18 fibrolipomas, four intramuscular lipomas, two minor salivary gland lipomas and one spindle cell lipoma. PCNA and ki-67 expression indexes were higher in spindle cell lipoma, intramuscular lipomas and fibrolipomas compared to common lipomas, but the differences were not statistically significant. All lesions were removed surgically and none showed recurrence, regardless of the various proliferative activities.

Atypical benign lipomatous tumors in the soft tissue: radiographic and pathologic correlation

This article describes the characteristic imaging findings and correlates them with the pathology in the nonfatty regions of benign atypical lipomatous tumors, which have different findings compared with typical lipomas and well-differentiated liposarcomas. For differentiating these tumors from typical lipomas and well-differentiated liposarcomas, it may be helpful to analyze nonfatty regions in benign atypical lipomatous tumors.

[Lipomatous tumors of soft tissues in the extremities and the waist in adults]

Lipomatous tumors of the upper and lower extremities in adults are frequent and lipoma is the most common soft tissue tumor. Most have a typical appearance at imaging but presentation and management may vary based on the exact histological subtype. The purpose of this paper is to review the main clinical, radiological and histological features of the different benign and malignant lipomatous tumors.

The genetics of lipomatous tumors

The current classification of lipomatous neoplasms has been validated by the identification of characteristic cytogenetic and molecular genetic profiles associated with various neoplasms within the family of lipomatous tumors. The review describes characteristic cytogenetic and molecular genetic profiles and discusses their significance. The clinicopathologic features of these tumors, which are described elsewhere, will not be included in this review.

The contribution of image cytometry to the characterization of clinical subgroups of lipomas

The aim of the present study was to investigate whether biological features determined through image cytometry are able to characterize clinical subpopulations of lipomas. Forty lipomas excised from 36 patients were studied. On the one hand, the tumors were clinically characterized by means of patient-related and pre- and post-operative features. On the other, the tumors were analyzed by means of the computer-assisted microscopy analysis of Feulgen-stained nuclei. This analysis generated 3 groups of biological quantitative variables describing morphonuclear aspects (i.e. the chromatin pattern of the cell nuclei), the nuclear DNA content (DNA ploidy level), and architectural features (such as the cell density and the topographical cell nuclei organization). Possible relations between the clinical and the biological features of the lipomas were investigated by means of univariate and multivariate statistical analyses. The results show the existence of such relations, in particular between the morphonuclear and architectural features of lipomas, on the one hand, and their consistency, volume and weight, on the other. Furthermore, multivariate analysis made it possible to distinguish two subpopulations of lipomas exhibiting different biological characteristics in terms of morphonuclear patterns.

Sialolipoma: a report of seven cases of a new variant of salivary gland lipoma

AIMS

We propose the designation 'sialolipoma' to establish and characterize a new category of benign lipomatous tumour occurring in salivary glands. Until now, these tumours have not been regarded as a distinct entity in the salivary glands.

METHODS AND RESULTS

We evaluated the clinicopathological and immunohistochemical features of seven sialolipomas among 2051 surgically resected primary salivary gland tumours deposited in our files. The seven patients with sialolipoma were five men and two women, aged 20-75 years (mean: 54.4 years). Five tumours had arisen in the parotid gland, one in the soft palate, and one in the hard palate. The tumours ranged from 10 to 60 mm (mean: 38 mm) in maximum diameter. Histologically, the tumours were characterized by a well circumscribed mass composed of glandular tissue and mature adipose elements. The adipose elements in the tumours arising in the parotid gland were more abundant than those arising in the minor salivary gland. The glandular components consisted of ductal, acinar, basal and myoepithelial cells, and closely resembled the cellular and structural compositions of normal salivary gland tissues. These findings were confirmed by immunohistochemical and ultrastructural studies. These components had no atypia, except for the presence of some minor variations, e.g. ductal ectasia with fibrosis and focal oncocytic metaplasia. In all cases, cell proliferative activity, as assessed by Ki67 (MIB1) immunostaining, was low. From these findings, it is likely that our cases were lipomas with secondary entrapment of the salivary gland elements. No recurrence was seen in all cases after superficial parotidectomy, or after surgical excision in the patients with palatal tumours.

CONCLUSIONS

We regard sialolipoma as a distinct variant of salivary gland lipoma that can occur in both the major and minor salivary glands. Superficial parotidectomy, or surgical resection in the case of palatal tumours, is an appropriate treatment for this benign tumour.

Fibrohistiocytic lipoma: twelve cases of a previously undescribed benign fatty tumor

A lipoma with a spindled proliferation within it, resembling known (myo)fibroblastic lesions such as fibrous histiocytoma or dermatofibrosarcoma protuberans, (ie, fibrohistiocytic lipoma), has not been previously reported. This tumor varies from other classic lipoma variants, including spindle cell lipoma, myolipoma, angiolipoma, and fibrolipoma. We examine the clinicopathologic findings of this new lipoma variant. The Soft Tissue Pathology Registry of the Armed Forces Institute of Pathology was searched for patients with "lipoma with fibrohistiocytic proliferation." Lesions that were better classified as other entities were excluded. Patient slides and clinical history, including associated lesions, family history, duration of symptoms, history of trauma, natural progression, and treatments, were reviewed. Immunohistochemistry was performed on cases with available material (n = 6). Twelve patients with fibrohistiocytic lipoma were included. All tumors revealed a well-distributed quilt-like proliferation or solid focus of slightly plump to relatively bland spindled cells with collagenous stroma in short fascicular and storiform growth patterns. These spindled cells resembled those seen in either fibrous histiocytoma or dermatofibrosarcoma protuberans. However, the spindled proliferation was all within a well-circumscribed lipoma. The lesions lack the dermal involvement or plump pleomorphism of fibrous histiocytoma and the dermal involvement or infiltrative growth pattern of dermatofibrosarcoma protuberans. The fatty component demonstrated heterogeneously sized adipocytes, as those seen in other lipomas. Inflammation and hemosiderin were minimal. Mast cells were not identified. The tumors were typically found in the subcutis of the trunk of men (10 of 12; one each on the wrist and leg; mean age, 31 years). The average size of the lesions was 3.0 cm, and they were present for a mean duration of 10 months prior to surgical excision. One patient had two concurrent lesions; all others had solitary tumors. Another patient had a intracranial dermoid cyst removed during childhood. Four patients had a personal or family history of hypercholesterolemia, hypertension, or myocardial infarction. There was no history of antecedent trauma. Cases studied were positive for vimentin, calponin (5 of 5), CD34 (3 of 5), and occasionally KP-1 or lysozyme in the spindled component, and all cases studied were negative for the actins, caldesmon, S-100 protein, desmin, cytokeratins, and epithelial membrane antigen. Although the actins were negative in our laboratory, the more sensitive calponin positivity suggests myofibroblastic phenotype of the spindled component of this lesion. CD34-positive fibroblasts were present in three of five cases. Of eight patients with follow-up, there were no recurrences; all patients were alive and free of disease over a mean of 10 years (range, 2 months to 31 years). We have identified a lipoma variant, fibrohistiocytic lipoma, that has not been previously described. In our experience the morphology and calponin positivity suggest myofibroblastic phenotype for the spindled cells, within a lipoma. This entity can be distinguished from fibrous histiocytoma, fibromatosis, dermatofibrosarcoma protuberans, spindle cell lipoma and other lipoma, and liposarcoma variants.

[Lipomatous tumors of the skin and soft tissue. New entities and concepts]

Mesenchymal neoplasms of lipogenic differentiation are the most common soft-tissue neoplasms in adults. In recent years a number of "new" entities and variants have been described. Their recognition is important to avoid diagnostic pitfalls and inappropriate therapy. Chondroid lipoma, myolipoma, and purely cutaneous spindle-cell/pleomorphic lipoma are biologically benign neoplasms which may mimic sarcomas morphologically. Despite high-grade morphology cutaneous liposarcomas carry a favorable clinical prognosis. Spindle cell liposarcoma is a rare variant of atypical lipomatous tumour (well-differentiated liposarcoma) and must be distinguished from dedifferentiated liposarcoma with metastatic potential and benign spindle cell lipoma. The advent of cytogenetic and molecular investigations of lipomatous neoplasms has contributed to a better understanding of the biology of these neoplasms and led to a modification of conventional classification schemes.

A clinicopathologic study of 45 pediatric soft tissue tumors with an admixture of adipose tissue and fibroblastic elements, and a proposal for classification as lipofibromatosis

The tumor described here as lipofibromatosis is a rare pediatric neoplasm that has been variously interpreted as a type of infantile or juvenile fibromatosis, a variant of fibrous hamartoma of infancy, and a fibrosing lipoblastoma. This report details the clinicopathologic features associated with 45 cases of this soft tissue entity. The study group consisted of 32 males, 12 females, and one person of unstated gender. The patients presented with a soft tissue mass (range, 1-7 cm) involving the hand (n = 18), arm (n = 8), leg (n = 7), foot (n = 6), trunk (n = 5), or head (n = 1). Eight tumors were evident at birth. The individuals ranged in age from 11 days to 12 years (median age, 1 yr) at the time of initial biopsy or resection. Microscopic examination revealed abundant adipose tissue with a spindled fibroblastic element that chiefly involved the septa of fat and skeletal muscle. The process generally did not cause extensive architectural effacement of fat as is common with conventional fibromatoses, and it did not have a primitive nodular fibromyxoid component as is characteristic of fibrous hamartoma of infancy. The fibroblastic element exhibited focal fascicular growth and typically had limited mitotic activity (< or = 1 mitosis/ 10 high-power fields) and cytologic atypia. Oftentimes, small collections of univacuolated cells were present at the interface between some of the fibroblastic fascicles and the mature adipocytes. The tumors entrapped vessels (n = 45), nerves (n = 44), skin adnexa (n = 16), and skeletal muscle (n = 18). Focal immunoreactivity was present in some tumors for CD99, CD34, alpha-smooth muscle actin, BCL-2, and less frequently, S-100 protein, muscle actin (HUC 1-1), and EMA. However, no reactivity was detected for desmin (D33 and D-ER- 1 clones), keratins, or CD57. Follow-up data were available for 25 individuals (median follow-up period, 6 yrs 7 mos) with regrowth of the tumor or persistent disease documented in 17 (72%). The following events were more common in the group with recurrent or persistent disease: congenital onset, male sex, hand and foot location, incomplete excision, and mitotic activity in the fibroblastic element. Although it is likely this tumor comprises part of the spectrum of what has been referred to in the literature as infantile/juvenile fibromatosis, its clinicopathologic features and, in particular, its distinctive tendency to contain fat as an integral component, warrant separate classification as a "lipofibromatosis."

Spinal lipomas in children

Spinal cord lipomas are a common cause of cord tethering that can lead to progressive neurological defects. The role of prophylactic surgery for spinal lipomas has recently been questioned. Between 1985 and 1999, 59 children underwent a total of 69 surgical procedures at the Birmingham Children's Hospital in Birmingham, UK. The spinal lipomas were classified into: 18 terminal, 17 transitional, 6 dorsal and 18 filum lipomas - including 12 who had a typical thickened filum terminale. At the first operation, 19 patients (32%) were asymptomatic, and 40 patients (68%) presented with symptoms. Surgical indications in the asymptomatic group included the presence of a dermal sinus tract or syrinx. Prophylactic surgery was undertaken in selected cases. The mean total follow-up for the group since the first surgical procedure was 61.8 months (range: 7.0-203.0 months). In the asymptomatic group, 26% of the patients had late neurological deterioration. Of the 14 patients with asymptomatic conus lipomas, 3 (21%) developed sphincter dysfunction and motor problems at long-term follow-up. In the symptomatic group, 68% improved, 20% remained unchanged, and 12% had late neurological deterioration. None of the 18 patients with symptomatic filum lipoma deteriorated postoperatively. However, 39% had bladder dysfunction, 54% had neuro-orthopaedic deformity, and only 15% returned to overall normal function at latest follow-up. Of the 27 patients with symptomatic conus lipomas, 67% improved, 15% remained stable, and 18% had late neurological deterioration. However, 74% had bladder dysfunction, 67% had neuro-orthopaedic deformity, and 45% had motor problems at long-term follow-up. Spinal lipomas can cause progressive neurological deficits irrespective of spinal untethering surgery. This study demonstrates that filum and conus lipomas have similar clinical presentation, but differ in their outcome following surgery. Filum lipomas are 'benign', for which surgery is safe and effective. Conus lipomas are more difficult to manage. When asymptomatic, our results suggest that prophylactic surgery does provide some protection from future neurological deterioration. When symptomatic, conus lipoma surgery is effective in stopping further deterioration. Improvement in neurological function can occur, but few patients return to normal overall function, and pre-existing sphincter dysfunction is not significantly altered by surgery.

Atypical subcutaneous fatty tumors

Atypical fatty tumors present problems of terminology and diagnosis. While atypical fatty tumors that are located in subcutaneous tissues have an extremely good prognosis, local recurrence and transformation to a higher grade tumor may occur. Allen et al document the morphologic features and behavior of 37 atypical subcutaneous fatty tumors and describe a system of grading. The commentary discusses the terminology of atypical fatty tumors, the relevance of the proposed grading system, and the significance of a spindle cell component in atypical subcutaneous fatty tumors.

Lipoblastoma: better termed infantile lipoma?

Lipoblastoma is a rare adipose tumor occurring exclusively in childhood. There have been no reports of metastases, making the designation "blastoma" confusing, since this term is usually reserved for malignant tumors. Two recent cases treated at our institution confirm its benign nature. In addition, a review of the literature supports the idea that the tumor may more accurately be described as an "infantile lipoma". Infantile lipoma better reflects many of the tumor's characteristics such as, its early occurrence, it's ability to mature into a simple lipoma, it's cellular composition of mainly mature adipocytes, and its benign course. Although lipoblastoma is an uncommonly encountered tumor, making an effort to change its name to infantile lipoma will result in a more a accurate term that will facilitate treatment.

Recent developments in soft tissue tumors

The field of soft tissue tumor pathology, despite the relative rarity of the lesions concerned, has grown considerably in recent years and has featured very prominently in the academic pathology literature. This stems from the facts that increasing diagnostic sophistication has allowed the continued refinement of classification schemes and the delineation of numerous previously unrecognized 'entities' and that the application of modern cytogenetic and molecular genetic techniques has revealed the remarkable importance of reproducible cytogenetic aberrations in our understanding of the pathobiology of this group of neoplasms. This presentation will aim to summarize data regarding some of the recently characterized entities as well as the major molecular genetic advances. Newly characterized 'entities' which are important because of the ease with which they are confused with lesions of very different biologic potential include chondroid lipoma, pleomorphic hyalinising angiectatic tumor, extrapleural solitary fibrous tumor, giant cell angiofibroma, cellular angiofibroma, retiform hemangioendothelioma, composite hemangioendothelioma and low grade fibromyxoid sarcoma. The 'hemangioendotheliomas' also represent an important area of conceptual evolution as we begin to more critically analyze the concept of borderline malignancy. Concerning molecular genetic advances, the most striking data to emerge are the frequency of tumour-specific reciprocal translocations, the frequency of biologically revealing cytogenetic aberrations in benign lesions and the emerging evidence of striking differences in cell cycle abnormalities in the different sarcoma types.

Classification of human liposarcoma and lipoma using ex vivo proton NMR spectroscopy

Prognostication in patients with liposarcoma is a complex and controversial subject based on recognition of lipoblasts, adipocyte nuclear atypia, and qualitative estimations of cellularity and cell size. We show here that for 30 patients with liposarcoma and 5 patients with lipoma, spectral differences on high-resolution, magic angle spinning proton nuclear magnetic resonance (hr-MAS 1H-NMR) spectroscopy relate to known biochemical changes and correlate with adipocyte tissue differentiation, histologic cell type, and cellularity. The NMR-visible level of triglyceride is shown to correlate with liposarcoma differentiation, since the triglyceride level in well-differentiated liposarcoma is 33-fold higher on average than for myxoid/round cell liposarcoma, which in turn is 6-fold higher than the dedifferentiated and/or pleomorphic subtypes. The NMR-visible phosphatidylcholine level serves as an estimate of total tissue cell membrane phospholipid mass and was found to correlate with liposarcoma subtype. Pleomorphic liposarcoma, the most aggressive and metastatic subtype, was found to have a threefold increase in NMR-visible phosphatidylcholine level compared with dedifferentiated liposarcoma. The level of NMR-visible phosphatidylcholine was twofold greater in well-differentiated liposarcoma compared with lipoma and was threefold larger for the hypercellular myxoid/round cell subtype compared with the pure myxoid histology. Thus, NMR-derived parameters of tissue lipid may be used for objective distinction of liposarcoma histologic subtype/grade and lipoma from liposarcoma. These biochemical parameters may ultimately improve prognostication in patients with liposarcoma.

Atypical subcutaneous fatty tumors: a review of 37 referred cases

We reviewed 37 referred, atypical, subcutaneous fatty tumors. There was a male preponderance (28:9). The median age was 51.5 years (26-83); the median duration of symptoms was 18 months (three weeks to 35 years); the median size was 5.5 cm (1.5-20) and the posterior cervico-dorsal areas (17 cases) was the commonest location. We divided tumors into five histological categories: (1) subcutaneous fibrolipomas with slight fibroblastic atypia (five cases); (2) subcutaneous spindle cell lipomas with atypia (mixed spindle cell/pleomorphic lipomas) without lipoblasts (three cases); (3) subcutaneous atypical well-differentiated fatty tumors (pure pleomorphic lipomas) without lipoblasts (nine cases); (4) subcutaneous atypical well-differentiated fatty tumors (pleomorphic lipomas) with lipoblasts (17 cases); (5) subcutaneous atypical fatty tumors with poorly differentiated or de-differentiated areas (three cases). Follow-up information was obtained in 25 cases (68%). The follow-up times were from three to 192 months (median 31). Five tumors (20%) recurred, two as the same and three as a higher histological category. Two were originally referred because of a recurrence. Four recurred once and one, initially a category 4 tumor, recurred twice as a category 5 tumor. Two category 1 and three category 4 tumors recurred. There were no recurrences in the other three groups. All recurrent tumors were located outside the cervico-dorsal areas. The sizes of two tumors that recurred were 2.8 and 3 cm and the time to first recurrence was from one to 85 months. Two recurrent tumors of high histological category were controlled by re-excision and either radiotherapy or combined chemotherapy and radiotherapy. This series suggests that atypical subcutaneous fatty tumors comprise a continuous and potentially transforming histological spectrum, which ranges from mildly atypical fibrolipomas through various mixed spindle cell and pleomorphic lipoma patterns to tumors indistinguishable from de-differentiated liposarcomas. Despite a sometimes alarming histological appearance, none in the present series metastasized.

[Lipoma, multiple lipomas and lipomatosis]

Lipomatous tumors are very frequent; simple lipoma is the most common variety. According to Enzinger, lipomatous tumors are classified into five different groups: simple lipomas, variant lipomas forms, heterotopic lipomas, infiltrating lipomas and lipomatosis, and finally hibernomas. Usually, lipomatous tumors are characterized by a slow, unpainful, growth. Classical treatment includes surgical resection. The clinical diagnosis is confirmed by histology. Liposucion can be a therapeutic option in certain cases.

Occult spinal dysraphism--the common combination of lesions and the clinical manifestations in 50 patients

Fifty patients (26 males, 24 females) aged from birth to 51 years with occult spinal dysraphism were identified. All had Magnetic Resonance (MR) scans carried out. The MR scans were examined to determine the vertebral level of the conus and to see if one or more of the following were present; lipoma, syrinx, dermoid, diastematomyelia, and meningocele. In 43 patients the conus lay below the level of L3, 23 had a lipoma, 23 a meningocele, 20 an open central canal in the spinal cord or a syrinx, 15 a diastematomyelia and 4 a dermoid. The commonest combination of lesions was a long cord, a syrinx or an open central canal in the spinal cord and a lipoma. The diastematomyelias were always associated with a long cord and had the highest incidence of vertebral body anomalies (60%). The most frequent recorded signs were deformities of the feet, short legs, wasting of the calf muscles, weakness of the legs, back pain and bladder dysfunction. Combinations of these occurred with all of the lesions although some had none. Whilst deterioration was seen in about half of the patients, acute deterioration was uncommon and was associated most frequently with a dermoid or an expanded syrinx.

Evaluation of surgery for the tethered cord syndrome using a new grading system

A new grading system is presented to assess the degree of untethering achieved at surgery for the 'tethered cord syndrome' based on intraoperative observation at the end of the procedure. Various pathophysiological mechanisms responsible for the 'tethered cord syndrome', as well as possible factors causing retethering were considered in developing this grading system. In Grade I the cord is considered to be fully untethered and the factors potentially responsible for retethering are eliminated, in Grade II partial untethering is performed and in Grade III untethering is unsuccessful. This grading system was used to assess the results of 22 consecutive operations performed to release a tethered cord between June 1991 and February 1995. The tethering factors encountered at surgery were: spinal lipoma in 14, diastematomyelia in five, a tight filum terminale in 10 and intradural adhesions in three instances. The grade of untethering was correlated with the type of pathology encountered, postoperative results, and whether previous surgery was performed or not. Previous surgery was found not to affect the rate of subsequent successful untethering.

Correlation between clinicopathological features and karyotype in lipomatous tumors. A report of 178 cases from the Chromosomes and Morphology (CHAMP) Collaborative Study Group

Soft tissue tumors commonly show cytogenetic abnormalities, some of which are tumor specific. Lipomatous tumors represent the largest category of soft tissue neoplasms, and numerous karyotypic aberrations have been identified. However, clear-cut correlation between morphology and karyotype has not been undertaken on a systematic basis in a double-blind setting. The morphological features and histological diagnosis of 178 lipomatous neoplasms were reviewed independently without knowledge of the clinical data. The consensus diagnoses were then correlated with the clinical findings and compared with the tumors' karyotypes, using G-banded preparations from short-term cultures. The data were collated by a multicenter collaborative group of pathologists, geneticists, and surgeons. Clonal chromosomal abnormalities were identified in 149 cases studied (84%) and, to a large extent, the karyotype correlated with the morphological diagnosis. Specifically, 26 (96%) of 27 myxoid liposarcomas and its poorly differentiated variants showed a t(12;16); 29 (78%) of 37 atypical lipomatous tumors (including 5 dedifferentiated cases) showed ring chromosomes; 74 (80%) of 93 subcutaneous and intramuscular lipomas had karyotypic aberrations affecting mainly 12q, 6p, and 13q; 7 of 8 spindle cell and pleomorphic lipomas had aberrations of 16q; 3 lipoblastomas showed 8q rearrangements; and 2 hibernomas showed 11q abnormalities. We conclude that cytogenetic abnormalities are common in lipomatous tumors, correlate reliably with morphological sub-type in many cases, and can be of diagnostic value in histologically borderline or difficult cases.

Lipomatous tumours of soft tissues: an update

This review summarizes the clinicopathological features of recently characterized variants of lipomatous tumours of soft tissue, attempts to deal with some difficult conceptual issues relating to adipocytic neoplasms and aims to provide an update on cytogenetic aspects of fatty tumours. Myolipoma is a rare benign neoplasm, occurring most frequently in adults in the deep soft tissue of the abdomen or retroperitoneum, and is composed of irregularly admixed mature adipose and smooth muscle tissues. Chondroid lipoma represents an unusual benign lesion occurring mainly in adult females subcutaneously or in deep soft tissue; it is easily mistaken for myxoid liposarcoma or extraskeletal myxoid chondrosarcoma. Spindle-cell liposarcoma is a variant of well-differentiated liposarcoma quite commonly found in subcutaneous tissue of the shoulder region and upper limbs and is composed of relatively bland-appearing spindle cells mixed with a well-differentiated liposarcomatous component. Recently there has been considerable debate about classification of lipomatous tumours. The term atypical lipoma was proposed for a group of well-differentiated non-metastasizing liposarcomas arising in surgically amenable soft tissues and for deep-seated atypical adipocytic neoplasms that show variation in adipocytic size and atypical stromal cells but lack lipoblasts. However, these neoplasms recur repeatedly and may dedifferentiate and thereby acquire metastatic potential. We use the diagnosis atypical lipoma with caution and propose to use the terms well-differentiated liposarcoma and atypical lipoma interchangeably. The relationship between myxoid and round-cell liposarcoma, which constitutes the morphological spectrum of a single entity, has been clarified but there remain considerable problems in defining likely clinical behaviour. The recent advances in cytogenetic characterization and classification of lipomatous tumours, which is already proving to be of diagnostic importance, are reviewed, and the genetic importance of the distinct chromosomal translocation in myxoid/round cell liposarcoma is briefly discussed.

Tethered cord syndrome: the low-lying and normally positioned conus

We have previously proposed the existence of the tethered cord syndrome in the presence of a conus medullaris in the normal position. Our 12-year series of 73 patients with the tethered cord syndrome included 13 patients in whom the spinal cord terminated at or above the L1-L2 disc space. We compare the characteristics of these 13 with those of the 60 patients whose spinal cord terminated below the L1-L2 disc space. The parameters for comparison included neurological status at presentation and follow-up, the presence of cutaneous stigmata of occult spinal dysraphism, vertebral anomalies, and others. The frequency of occurrence of each parameter in the normally positioned group was essentially the same as its occurrence in the low-lying group.

Cytogenetic aberrations in 188 benign and borderline adipose tissue tumors

Chromosome studies of lipomas have revealed an extensive cytogenetic heterogeneity. To investigate the frequencies of previously recognized cytogenetic subgroups and to find out if more recurrent rearrangements can be identified, we have analyzed cytogenetically short-term tissue cultures of 237 samples from 188 adipose tissue tumors obtained from 142 patients. Only one of 58 tumors from 18 patients with multiple lipomas (more than two tumors) had karyotypic changes. Among the sporadic lipomas, 20 tumors had supernumerary ring chromosomes of unknown origin, 55 had different aberrations involving chromosome segment 12q13-15, 11 had changes of 6p or chromosome 13, but no rings or 12q13-15 changes, and 14 had various other aberrations. Ring chromosomes were found in all cytogenetically abnormal lipomas histologically classified as atypical and in nine tumors classified as typical lipoma or spindle cell lipoma. Recombinations between 12q13-15 and a few other bands or segments were seen more than once: 3q27-28 (15 tumors), 2p22-24 and 2q35 (four tumors), 1p32-34 and 13q12-14 (three tumors), and 5q33 (two tumors). Recombinations of 12q13-15 with 2q35 and 13q12-14 have not been described before. Of eight tumors with chromosome 13 aberrations, five had loss of 13q material. Aberrations of 12q13-15, 6p, and/or chromosome 13 were found simultaneously in nine tumors. Two to four samples from the same tumor were investigated in 29 tumors with clonal aberrations. Thirteen of these tumors displayed clonal evolution, also noted in another 17 tumors in which only one sample had been investigated. Thus clonal evolution occurred in 30% of the tumors and was particularly frequent in atypical lipomas.

Intracranial lipomas with teratomatous elements

We report two cases of patients with intracranial tumors that share features with lipomas and teratomas. Although rare reports of lipomas with "hypertrophic nerves" and "teratoid tumors" have been recorded, these two cases are unusual because they contain mature neuroectoderm (choroid plexus, peripheral nerve) and mesoderm (skeletal muscle). The findings are discussed and modern classification schemes are presented. We believe that the cases are examples of a transition between lipoma and teratoma.

Parosteal lipomas: a new perspective

Parosteal lipomas, benign adipose tissue tumors situated directly on bone cortex, are unusual neoplasms that appear to emerge from multidirectional mesenchymal "modulation" within the periosteum. These tumors have been described as "periosteal lipomas", "chondrolipomas of soft tissue" and "lipomas of nerves" but they are most commonly believed to originate from the periosteum. Although over 100 of such tumors have been described in the literature, they have not been the subject of a comprehensive review, nor their potential for chondroid modulation and enchondral ossification emphasized. A review of 14 parosteal lipomas from the Bone Tumor Registry, Armed Forces Institute of Pathology, indicates these tumors are frequently associated with chondroid and/or osseous modulation, which permits subclassification into 4 distinct variants. Each of the 4 subtypes (I: No Ossification; II: Pedunculated Exostosis; III: Sessile Exostosis; IV: Patchy Chondro-Osseous Modulation) is illustrated to demonstrate the morphologic basis for radiologic/pathologic correlation and subclassification. A brief overview of the literature and pathogenesis of this unusual lesion is presented and discussed.

Curvilinear and tubulonodular varieties of lipoma of the corpus callosum: an MR and CT study

Until recently all callosal lipomas were grouped together. However, these lipomas can be clearly separated into two groups having different morphologies and associated brain anomalies. One group consists of anteriorly situated round or cylinder-shaped lipomas, termed tubulonodular. These lipomas are generally greater than 2 cm in diameter and have a high incidence of corpus callosum dysgenesis, frontal lobe anomalies, and frontal encephaloceles. The second group comprises thin, posteriorly situated lipomas curving around the splenium and are termed curvilinear. The curvilinear lipomas are generally associated with a normal corpus callosum and otherwise have a low incidence of associated anomalies. When anomalies do occur, they tend to be less severe than with the tubulonodular lipomas. We present four cases of curvilinear lipomas and review similar cases in the literature to explain why lipomas of the callosal region have such a variety of associated anomalies and morphologies. Our findings support the idea that both groups of lipomas develop in the region of the origin of the corpus callosum but form at different times during gestation, with the tubulonodular ones forming earlier and thus being associated with more severe cerebral anomalies.

Leptomyelolipoma: analysis of 20 cases

Leptomyelolipoma (lumbosacral lipoma) is a common form of spinal dysraphism. The deficits produced include sensory, motor, bowel, and bladder dysfunction, and vary in incidence between the pediatric and adult populations. Twenty patients treated surgically at the Mount Sinai Hospital between 1972 and 1988 are reviewed. Fifty percent were 12 years of age or less and 50% were older than 18 years of age. The surgical approach was designed to accomplish untethering of the conus medullaris, debulking of the lipomatous mass compressing the cord, reconstruction of the dural canal, and reapproximation of the paraspinal muscles and lumbosacral fascia to prevent future trauma. Postoperatively, no patient experienced deterioration of neurological function. Of the symptomatic patients. 67% displayed dramatic improvement or became asymptomatic and 33% experienced stabilization of their deficits. The symptoms most resistant to surgical correction were orthopedic foot deformities and bowel dysfunction, whereas bladder dysfunction, motor weakness, and radiculopathies were most amenable to surgical therapy. Early surgical repair is recommended in these cases to forestall irreversible neurological damage.

Fine needle aspiration cytology of thymolipoma. A case report

A case of thymolipoma in a 14-year-old girl diagnosed prospectively by fine needle aspiration (FNA) biopsy is reported. The cellular constituents of the aspirate, lymphocytes and epithelial cells, were characterized by routine cytology and immunocytochemistry. Although primarily based on the FNA cytology, the diagnosis was supported by the patient's clinical history and the radiographic demonstration of a fat density mass. This appears to be the first description of thymolipoma in a fine needle aspirate.

Thoracic fatty lesions - some usual and unusual appearances

Since the advent of computed tomography (CT) special attention has been given to fatty lesions because of their specific coefficient of attenuation (-100 to -30 Housfield units) permitting a definitive non-interventional diagnosis. Many reports have appeared in connection with unusual conventional radiographic images related to lipid lesions as demonstrated by CT. We reviewed the different features of fatty accumulations in the thorax and report on 15 lesions, not including a number of large pleuropericardial fat pads, that we have encountered in our practice between January 1976 and December 1979. Two patients underwent surgery. The diagnosis was otherwise established by CT. All the lesions were benign. A classification is suggested.

The pathology of head and neck tumors: fibroadipose tissue and skeletal muscle, Part 8

Benign and malignant tumors originating from mesenchymal cells destined to become lipoblasts and myoblasts affect the head and neck with contrasting frequencies. Lipomas and especially liposarcomas are unusual lesions above the clavicles but when found there behave in a biologic manner identical to that of their counter-parts at other anatomic sites. Myogenic tumors, on the other hand, have a predilection for the head and neck, and for rhabdomyosarcomas this predilection is accentuated in childhood. Combination therapy of rhabdomyosarcomas has obviated radical surgery as a method of treatment, and many sites in the head and neck have benefited prognostically by this treatment. Success, however, is dependent on clinical stage of disease, and rhabdomyosarcomas of the nasopharynx, paranasal sinuses, and middle ear remain more resistant to short-term cures because of the extent of the neoplasm. A review of the clinicopathologic aspects of granular-cell tumors and alveolar soft-part sarcomas is also presented because it has been suggested that these tumors have a myogenous origin.