Oncogenic osteomalacia: localization of underlying peripheral mesenchymal tumors with use of Tc 99m sestamibi scintigraphy

OBJECTIVE

To highlight a strategy for potential detection of mesenchymal tumors in oncogenic malacia, as illustrated by 3 cases.

METHODS

Three case reports are presented in which successful localization of the offending neoplasm was accomplished by using whole-body Tc 99m sestamibi scanning. Alternative localization techniques are also reviewed.

RESULTS

Oncogenic osteomalacia occurs infrequently and is caused by neoplasms that secrete phosphatonins, substances that interfere with proximal tubular resorption of phosphorus and can result in phosphaturia, hypophosphatemia, reduced 1,25-dihydroxyvitamin D concentration, and osteomalacia. Removal of the underlying neoplasm results in complete resolution of all biochemical, pathologic, and physical manifestations of this disorder, as shown in our 3 patients. Because the neoplasms are small and can occur in any tissue compartment, they are difficult to localize, a feature that often results in therapeutic failure.

CONCLUSION

We conclude that use of whole-body Tc 99m sestamibi scanning may be an appropriate and cost-effective initial strategy for the localization of peripheral phosphatonin-secreting tumors.

Fat in the liver: diagnosis and characterization

The purpose of this article is to provide an update on imaging techniques useful for detection and characterization of fat in the liver. Imaging findings of liver steatosis, both diffuse steatosis and focal fatty change, as well as focal fatty sparing, are presented. In addition, we will review computed tomography (CT) and magnetic resonance (MR) findings of focal liver lesions with fatty metamorphosis, including hepatocellular carcinoma, hepatocellular adenoma, focal nodular hyperplasia, angiomyolipoma, lipoma, and metastases.

Rearrangement of chromosomal region 8q11-13 in lipomatous tumours: correlation with lipoblastoma morphology

Cytogenetics is of considerable value when diagnosing lipomatous tumours, as different tumour types have different more or less specific chromosomal abnormalities. One such entity is lipoblastoma, which is a benign lipomatous tumour that often exhibits rearrangements of chromosome bands 8q11-13, and the gene PLAG1 has been implicated as the target of these chromosomal changes. All lipomatous tumours karyotyped at the Norwegian Radium Hospital were reviewed, looking for rearrangements of 8q11-13. Five tumours exhibiting chromosomal abnormalities affecting this region were found. Only one of them was morphologically diagnosed as a lipoblastoma, two being classified as lipomas, one as a hibernoma, and one as a well-differentiated liposarcoma. The two tumours successfully analysed with bacterial artificial chromosomes (BACs) covering the gene PLAG1 showed involvement of this gene in the rearrangement. The findings raise the question as to what extent the diagnosis lipoblastoma should be based on histopathological or cytogenetic/molecular data or a combination thereof. When karyotypic information from this series was combined with available literature data, it was found that the sensitivity of 8q11-13 rearrangements for diagnosing lipoblastomas when found in a lipomatous tumour was 77% and that the corresponding specificity was 98%. The validity of these calculations of the diagnostic information provided by the cytogenetic findings is, of course, totally dependent on the morphological diagnosis made in each case. Regardless of what the precise phenotypic diagnosis was, it is suggested that lipomatous tumours with 8q11-13 rearrangement constitute a distinct pathogenetic entity. When selective therapies tailor-made against the specific pathogenetic rearrangement become available, it will become mandatory to pay more attention to the genetic constitution of the tumour cells than to their phenotypic appearance.

Recurrent maturing perineal lipoblastoma

Lipoblastoma is a rare benign neoplasm of fetal adipose tissue that we see mostly in infants and young children less than 3 years of age. Most lipoblastomas occur on the extremities, trunk, head and neck, and various other organs have been described. We report a case of a recurrent perineal lipoblastoma in a 2.5-year-old boy, which showed maturation of the lipoblasts as compared to the primary tumor.

Lipoblastoma of Infancy Mimicking Hemangioma of Infancy

Lipoblastomas are rare benign tumors of infancy that usually affect children younger than 3 years. Most lipoblastomas (70%) occur on the extremities. Lipoblastomas may mimic other infantile tumors, including hemangiomas, hibernomas, lipomas, and liposarcomas, and correct diagnosis is necessary to ensure appropriate treatment. Lipoblastomas fall under 2 discrete subtypes: well-circumscribed lipoblastomas and diffuse lipoblastomatosis. Both types present with firm, nontender masses of lobulated, well-circumscribed soft tissue. Histologically they can be highly vascularized with plexiform capillaries, often with an individual feeder artery to each lobule. Complete surgical removal is the recommended treatment. Only 2 cases of lipoblastomas of the cheek have been reported in the English-language literature. We present the case of a young child with a cheek lipoblastoma, emphasizing the importance of correct diagnosis and highlighting techniques used to provide suitable treatment.

From the archives of the AFIP: benign musculoskeletal lipomatous lesions

Benign lipomatous lesions involving soft tissue are common musculoskeletal masses that are classified into nine distinct diagnoses: lipoma, lipomatosis, lipomatosis of nerve, lipoblastoma or lipoblastomatosis, angiolipoma, myolipoma of soft tissue, chondroid lipoma, spindle cell lipoma and pleomorphic lipoma, and hibernoma. Soft-tissue lipoma accounts for almost 50% of all soft-tissue tumors. Radiologic evaluation is diagnostic in up to 71% of cases. These lesions are identical to subcutaneous fat on computed tomographic (CT) and magnetic resonance (MR) images and may contain thin septa. Lipomatosis represents a diffuse overgrowth of mature fat affecting either subcutaneous tissue, muscle or nerve, and imaging is needed to evaluate lesion extent. Lipoblastoma is a tumor of immature fat occurring in young children, and imaging features may reveal a mixture of fat and nonadipose tissue. Angiolipoma, myolipoma, and chondroid lipoma are rare lipomatous lesions that are infrequently imaged. Spindle cell and pleomorphic lipoma appear as a subcutaneous lipomatous mass in the posterior neck or shoulder, with frequent nonadipose components. Hibernoma appears as a lipomatous mass with serpentine vascular elements. Benign lipomatous lesions affecting bone, joint, or tendon sheath include intraosseous lipoma, parosteal lipoma, liposclerosing myxofibrous tumor, discrete lipoma of joint or tendon sheath, and lipoma arborescens. Intraosseous and parosteal lipoma have a pathognomonic CT or MR appearance, with fat in the marrow space or on the bone surface, respectively. Liposclerosing myxofibrous tumor is a rare intermixed histologic lesion commonly located in the medullary canal of the intertrochanteric femur. Benign lipomatous lesions may occur focally in a joint or tendon sheath or with diffuse villonodular proliferation in the synovium (lipoma arborescens) and are diagnosed based on location and identification of fat. Understanding the spectrum of appearances of the various benign musculoskeletal lipomatous lesions improves radiologic assessment and is vital for optimal patient management.

2-Deoxy-2-[F-18]fluoro-d-glucose—Positron Emission Tomography of the Head and Neck: An Atlas of Normal Uptake and Variants

In the evaluation of tumors of the head and neck region, positron emission tomography (PET) using 2-deoxy-2-[F-18]fluoro-D-glucose (FDG) is increasingly playing a valuable clinical role. However, assessment of this region can be challenging because of the large number of structures in this area which may demonstrate physiologically increased uptake of FDG. Furthermore, these structures are generally small, and uptake patterns can be quite variable, rendering the head and neck region one of the most difficult areas of the body to assess with FDG-PET. To assist in this endeavor, a pictorial of normal FDG uptake, including commonly encountered variants, is presented.

Atypical lipomatous tumor with rare structural rearrangements involving chromosomes 8 and 12

Atypical lipomatous tumor (ALT), an intermediate malignant neoplasm of soft tissues, is characterized by the presence of supernumerary ring and giant marker chromosomes. These supernumerary chromosomes consistently contain amplified 12q-material in association with amplified segments from a variety of other chromosomes. However, a few cases of ALT with other types of chromosomal rearrangements have been reported earlier. We report on new types of structural aberrations in a case of ALT. In a pseudodiploid karyotype, there were two aberrant chromosomes, both consisting of alternating chromosome 8 and 12 sequences as shown by multicolor fluorescence in situ hybridization (FISH). The complex rearrangement was not only the result of multiple breaks and reunions of these chromosomes, but was also associated with a gain of chromosome 12 sequences. FISH analyses revealed that the number of MDM2 signals was slightly elevated (median, 5). There were three intact copies of HMGA2 and one additional copy of the 5' part of the gene. These findings are consistent with previous reports that the ALT phenotype may be associated with a low or moderate level of gene amplification, whereas truncation of HMGA2 has been observed in both ALTs and benign lipomas. The aberrations in the present case were stable, although rare cells with higher MDM2 copy numbers were detected. Whether ALTs with these types of aberrations have a lower risk of tumor progression than ALTs with the notoriously mitotically unstable ring and giant marker chromosomes remains to be investigated.

Tenascin C and cathepsin d expression in adipocytic tumors: an immunohistochemical investigation of 43 cases

Cathepsin D (CatD) and tenascin C (Tn-C) have been implicated in invasion and metastasis of carcinomas. However, little is known about CatD and Tn-C distribution in mesenchymal tumors. Therefore, we aimed to investigate the expression of Tn-C and CatD in adipocytic tumors. Tn-C and CatD expressions in 27 lipomas, 5 atypical lipomatous tumor/well-differentiated liposarcomas (ALT/WDLS) and 11 liposarcomas (LS) were evaluated by immunohistochemistry and scored semiquantitatively. CatD expression was higher in ALT/WDLS than in lipomas (p<0.001), and higher in LS than in ALT/WDLS (p=0.009). Stromal Tn-C expression was higher in ALT/WDLS than in lipomas (p=0.02), but no difference was observed between ALT/WDLS and LS (p>0.05). These results indicate that Tn-C and CatD may be markers of locally aggressive or malignant behavior in adipocytic tumors.

Lipoblastoma in an 11-month-old infant

Lipoblastoma and lipoblastomatosis are rare benign mesenchymal tumors of embryonal white fat, which normally affect children under 3 years. We report an 11-month-old boy who was presented with a painless lump in the suprapubic region, which was diagnosed on ultrasound as herniated omental fat or lipoma.

[Cytomorphological features of the fatty tissue tumors of the liver]

The necrotizing soft tissue infection caused by anaerobic microorganisms or by mixed aerobic-anaerobic flora is one of the most severe infections in surgical practice with a mortality rate up to 75%. Of great importance for successful treatment are the early diagnosis followed by aggressive debridement and adequate antibacterial therapy. Depending on the studies of 358 isolates made in the Clinic of Septic Surgery, we specify the most often used antibiotics in cases of severe anaerobic surgical infection. It is established that the incidence of this severe infection is unpredictable and its spreading depends on the immune answer the concomitant illnesses and the previous undertaken surgeries of the patient.

Mesenchymal Tumours of the Thorax:CT Findings and Pathological Features

Mesenchymal tumours of the thorax are uncommon and may originate from the muscle, bone, cartilage, vessel, nerves, fat and fibrous tissue. These tumours occur at different sites including the lung, pleura, mediastinum or chest wall. Mesenchymal tumours tend to show protean and non-specific imaging characteristics. However, in some instances, the imaging characteristics of the tumour may allow a specific diagnosis to be made, such as with lipoid or vascular tumours.

Chiari I malformation associated with thoracic epidural cord lesion: case report

Many spinal cord lesions have been described previously, in association with Chiari I lesions. The authors report a unique case of a 29-year-old patient with a Chiari I malformation and an upper thoracic epidural lesion causing headaches, dysphagia and Brown-Sequard syndrome. The patient underwent a suboccipital decompression as well as a thoracic laminectomy and resection of the epidural lesion. Pathologic analysis revealed that the thoracic lesion was fibro-adipose tissue. A review of the literature failed to show any other similar cases. We discuss the possible etiologies of this case.

Lipoblastoma in a 23-year-old male: distinction from atypical lipomatous tumor using cytogenetic and fluorescence in-situ hybridization analysis

Lipoblastoma is a rare benign tumor that occurs primarily in infancy and early childhood. We present the rare presentation of a 12 cm sized intramuscular lipoblastoma of the thigh in a 23-year-old patient. On histology, the tumor strongly resembled an atypical lipomatous tumor due to the presence of lipoblasts and atypical stromal nuclei. The very focal lobulation and myxoid change presented the only histological hint towards a lipoblastoma. Cytogenetic and subsequent FISH evaluation of the tumor cells showed a 46,XY, t(8;15) (q12;q25) as chromosomal change with rearrangement of the PLAG1 gene. The present case indicates that lipoblastoma should enter the differential diagnosis of an 'atypical' deep seated fatty tumor in adults. The diagnostic value of cytogenetic/molecular analysis in the differential diagnosis of lipomatous tumors is underscored as well.

Fatty tissue breast lesions

Hamartoma, lipoma and fat necrosis are benign fatty tissue lesions that may present as breast lumps. The mammographic appearance may be distinctive allowing imaging diagnosis without biopsy. The characteristic feature of hamartoma is that of a compressible mass containing radiolucent fat interchanged with dense fibrous connective tissue surrounded by a thin radioopaque pseudocapsule. Lipomas are radiolucent with well-defined thin smooth capsule. Twenty-seven percent of fat necrosis appears as discrete round or oval radiolucent oil cyst with thin capsule and egg-shell calcification.

Lipomatous variant of nasopharyngeal angiofibroma: a case report

Nasopharyngeal angiofibroma is an uncommon benign vascular tumor that occurs in adolescent boys and young men. We describe an unusual histological variant of this entity characterized by a prominent adipose tissue component. The patient was a 35-year-old man with a 20-year history of nasal obstruction. Results of physical examination and angiography demonstrated a nasal mass consistent with a nasopharyngeal angiofibroma. We discuss the differential diagnoses pathologically for this lesion.

Caveolin expression is common among benign and malignant smooth muscle and adipocyte neoplasms

The caveolins belong to a newly described group of membrane-scaffolding proteins. Their presence in benign endothelial cells has been used to discriminate benign from malignant vascular neoplasms. The extent of caveolin expression in cutaneous mesenchymal neoplasms has not yet been evaluated, and thus the diagnostic utility of these antibodies is not yet known. In our study, we immunohistochemically examined a spectrum of tumors derived from smooth muscle and adipocytes for caveolin expression. We found that both benign and malignant smooth muscle tumors and tumors comprised of adipocytes expressed caveolins. The presence of this protein in a range of mesenchymal neoplasms is important to know about as this decreases the reported specificity of a positive finding. It is doubtful that caveolin down-regulation contributes to the pathogenesis of liposarcomas and leiomyosarcomas. This finding also may suggest a common origin between endothelial cells and other mesenchymal cells.

Fat attenuation lesions of the mediastinum

The identification of fat within a focal or diffuse mediastinal lesion significantly narrows the differential diagnosis. In many cases, a specific diagnosis can be suggested on the basis of CT findings. In this article, we illustrate and review the characteristic CT features of common and uncommon fat attenuation lesions of the mediastinum, including focal masses and diffuse abnormalities.

Adrenal lipomatous tumours: a 30 year clinicopathological experience at a single institution

AIMS

Fatty tumours of the adrenal gland are uncommon and their features have received little attention in the literature. The aim of this study is to analyse the features of adrenal lipomatous tumours.

METHODS

The histological features of primary adrenal tumours reported over a 30 year period (1970 to 1999) in Queen Mary Hospital, Hong Kong were reviewed and the clinicopathological features of adrenal lipomatous tumours were analysed.

RESULTS

Adrenal lipomatous tumours were noted in 20 patients (12 men, eight women), and they accounted for 4.8% of the primary adrenal tumours reported. The adrenal fatty tumours comprised 11 myelolipomas, three lipomas, three teratomas, two angiomyolipomas, and one liposarcoma. Calcification or bone was noted in one third (seven of 20) of the adrenal tumours. In some fatty tumours (myelolipoma and angiomyolipoma), the fatty component may be inconspicuous. This is the first report in the English literature of angiomyolipoma and liposarcoma of the adrenal gland.

CONCLUSIONS

Different types of fatty tumours were noted in the adrenal gland. A high index of suspicion should be maintained with an aim of surgical treatment for selected patients with large and symptomatic adrenal lipomatous lesions. Histological confirmation is needed for diagnosis.

[Spindle cell lipoma and 13q deletion: diagnostic utility of cytogenetic analysis]

AIM

Spindle cell lipomas are rare adipose tissues tumors. Histologically, these lesions are composed of mature adipocytes and spindle cells associated with collagen bundles. Spindle cell lipomas are benign tumors that can be difficult to distinguish from malignant tumors such as spindle cell liposarcomas, myxoid liposarcomas or well-differentiated liposarcomas.

RESULTS

We report herein the description of two new cases. The first case was a deeply situated and infiltrating tumor located in the retromastoidian area. The karyotype showed the presence of two chromosomal abnormalities, a partial deletion of the long arm of chromosome 13, del(13)(q12) and a balanced reciprocal translocation t(2;6)(p16~21;p21). The second case was a subcutaneous tumor of posterior cervical localization. The karyotype showed a 13q deletion associated with a complex rearrangement of chromosomes 5, 6 and 10. The presence of the 13q deletion allowed us to confirm the diagnosis of spindle cell lipoma in both cases. This deletion has been previously described in six out the eleven published karyotype reports. The 13q deletion is usually associated with partial monosomy 16. The present case confirms that it can occur independently. The 6p21 rearrangement may also play a role in the pathobiology of this tumor, as suggested by the positive HMGIY expression detected by immunohistochemistry.

CONCLUSION

Our study further illustrates that spindle cell lipomas can infiltrate the surrounding muscle and emphasizes the usefulness of cytogenetic analysis in the differential diagnosis of soft tissue tumors.

Lipoblastoma and lipoblastomatosis in infancy and childhood: histopathologic, ultrastructural, and cytogenetic features

Lipoblastoma is a relatively rare tumor that occurs in infancy and early childhood and arises from embryonic white fat. Although a benign tumor, lipoblastomas tend to recur and may resemble myxoid liposarcoma. The authors report 26 cases over a 15-year period at Texas Children's Hospital. There was a slight female predilection (14F:12M). The most common symptom was a painless mass with or without increasing size. The trunk, extremities, head and neck, retroperitoneum, inguinal canal, peritoneal cavity, and lung were the tumor sites. Most tumors were circumscribed lipoblastomas and the minority were diffuse infiltrative lipoblastomatosis. Reexcision for residual or recurrent tumor was necessary more frequently in patients with lipoblastomatosis. Histopathologic examination and ultrastructural examination revealed cellular neoplasms composed of immature adipocytes with relatively well-defined septa, frequent lipoblasts, a fine vascular network, and often a myxoid appearance resembling myxoid liposarcoma. Cytogenetics was performed in 4 cases with chromosome 8q abnormality being most common. The major concern with lipoblastoma in children is to completely excise the tumor to avoid leaving residual tumor and to prevent recurrences. Confusion with myxoid liposarcoma, well-differentiated liposarcoma, and typical lipomas may occur. Although asymptomatic, lipoblastomas may cause dysfunction of other organ systems due to mass effect. Complete surgical excision with at least 2 years of follow-up is the preferred therapy.

Immunohistochemical profile of galectin-8 expression in benign and malignant tumors of epithelial, mesenchymatous and adipous origins, and of the nervous system

This study aims to investigate whether the immunohistochemical expression of galectin-8 could be used as a diagnostic marker in tumor tissues of various histogenetic origins including specimens from epithelial (n=145), mesenchymatous (n=16), adipous (n=10) and central and peripheral nervous system (n=25) tissue, and 4 mesotheliomas. Immunohistochemical reactions were carried out with a polyclonal anti-galectin-8 antibody and histological slides from tissues derived from the files of the Laboratory of Anatomopathology of University Erasmus Hospital, Brussels. Formalin-fixed paraffin-embedded tissues of 45 normal cases as well as 41 benign and 114 malignant tumors were studied. Marked decreases in immunohistochemical galectin-8 expression were observed in colon (p=0.001), pancreas (p=0.007), liver (p=0.0008), skin (p=0.002) and larynx (p=0.02) tissue when comparing malignant tissue to normal tissue and/or benign tumors. The reverse relationship was observed for breast tissue (p=0.007). No statistically significant differences (p>0.05) were detected when comparing normal tissue and/or benign to malignant tumors in lung, bladder, kidney, prostate and stomach tissue. Significant galectin-8 expression was also measured in non-epithelial tissue including tumors of the central and peripheral nervous system as well as in skeletal muscle and mesotheliomas. Immunohistochemical monitoring of galectin-8 thus reveals an organ-type-dependent regulation of expression upon malignant transformation of various tissue types of epithelial origin. This observation will prompt further studies to delineate any relationship with prognosis.