Pure hibernoma of the breast: insights about its origins

Hibernomas are rare benign tumors composed of cells reminiscent of brown adipose tissue. In the mammary gland, hibernomas are extraordinary rare, with only 4 cases reported previously. We report the fifth case in a 37-year-old woman who presented with a slowly growing mobile mass in her right breast. A 2.2 cm well-circumscribed lobulated mass was completely removed. The histopathologic analysis showed the full characteristics of the hibernoma. A review of the clinicopathologic features of hibernomas, its relation to brown adipose tissue in humans, and considerations about its histogenesis are made.     

Adenohibernoma: a rare breast tumor

Adenohibernoma of the breast is a very rare tumor composed of brown fat tissue and intermingled glandular tissue. There are only 2 case reports in literature. This study reports the third case of adenohibernoma of the breast, which is not accompanied by breast cancer differing from the previous cases. And, to the best of the authors' knowledge, this is also the first case of adenohibernoma of the breast that has demonstrated adipophilin expression immunohistochemically.     

Peripheral T-cell lymphoma presenting as a soft-tissue mass of the extremity

An 87-year-old man was found to have a lymphoma in the deep soft tissue of the right shoulder with concomitant central nervous system involvement. There was no evidence of cutaneous, peripheral lymph node, mediastinal, abdominal, or bone marrow involvement. Light microscopic, ultrastructural, and immunohistochemical evaluation characterized the neoplasm as a peripheral T-cell lymphoma. Lymphomas presenting in soft tissue are rare, and the few well-documented cases in the literature are of B-cell origin. We report a T-cell lymphoma presenting in the soft tissue of the extremity, and delineate its clinicopathologic features.     

Leiomyosarcoma arising from soft tissue tumor of the mediastinum

The occurrence of a leiomyosarcoma (LMS) in soft tissue of the mediastinum is rare. We report a 60-year-old woman with an LMS in mediastinal soft tissue who died 8 months after surgical removal. Pathological, immunohistochemical, and electron microscopic features of this rare tumor are described.     

Thymohemangiolipoma, a rare histologic variant of thymolipoma: a case report and review of the literature

We report a case of a thymic neoplasm in an 18-year-old woman who presented with chest discomfort and an anterior mediastinal mass. The surgically resected tumor showed abundant adipose tissue admixed with thymic tissue and numerous medium-caliber blood vessels. We consider this tumor a rare variant of thymolipoma and designate it as thymohemangiolipoma. Because of its benign nature, it should be distinguished from other mediastinal lesions.     

Mesenchymale Tumoren des Mediastinums

Mesenchymal neoplasms of the thymus and mediastinum account for only 2?% of neoplasms of the mediastinum and are therefore very rare. With very few exceptions the histology, immunohistochemistry and (based on current knowledge) molecular biology of mediastinal soft tissue tumors are not different from their counterparts in other organs. Characteristic features are more concerned with clinical epidemiological and therapeutic aspects as well as the multitude of possible differential diagnoses. With the exception of organ-specific tumors, such as gastrointestinal stromal tumors (GIST), virtually all entities encountered in peripheral soft tissues can also arise in the mediastinum. Primary mediastinal soft tissue sarcomas (STS) must be distinguished from secondary radiation-induced STS after irradiation, e.?g. for breast cancer and Hodgkin’s lymphoma and from STS arising as somatic type malignancies in mediastinal germ cell tumors     

Brown-Pigmented Mycobacterium mageritense as a Cause of Prosthetic Valve Endocarditis and Bloodstream Infection

Mycobacterium spp. are a rare cause of endocarditis. Herein, we describe a case of Mycobacterium mageritense prosthetic valve endocarditis. This organism produced an unusual brown pigment on solid media. Cultures of valve tissue for acid-fast bacilli might be considered in some cases of apparently culture-negative prosthetic valve endocarditis.     

Poorly differentiated monophasic synovial sarcoma of the mediastinum

Poorly differentiated synovial sarcoma is a diagnostically challenging neoplasm. Most commonly they occur in the soft tissue of the extremities and are rare in the mediastinum. They can be indistinguishable from other "round cell tumors" based on the morphology alone or at times by immunohistochemical studies. Here in, we report an extremely rare case of metastatic poorly differentiated monophasic synovial sarcoma of the mediastinum without a known primary in a 30-year-old man. The imaging studies on admission showed 10 × 9.5 cm anterior mediastinal mass with multiple nodules in the lung and pleura along with multiple enlarged mediastinal and axillary lymph nodes. Histopathologic and immunohistochemical analysis supported the diagnosis of poorly differentiated synovial sarcoma, which was further confirmed by molecular genetic analysis.     

Accumulation of brown adipose tissue and nutritional status. A prospective study of 366 consecutive autopsies.

Increased amounts of brown adipose tissue have been reported to occur in association with several diseases. The objective of the present study was to determine whether brown adipose tissue accumulation is related to nutritional status. Histologic sections of periadrenal tissue prospectively obtained at consecutive autopsies from 366 adults were examined. The cases were separated into three groups: malnourished (101 autopsies), normotrophic (128 autopsies), and obese (137 autopsies), according to the Quetelet index. Of these patients, 89 had brown adipose tissue accumulation, 35 were malnourished, 32 were normotrophic, and 22 were obese. The results showed a correlation between brown adipose tissue and patient nutritional status and a higher brown adipose tissue accumulation in malnourished patients. Cardiovascular disease was the most common type of illness present in the cases with brown adipose tissue accumulation.     

Adenocarcinoma arising in an ectopic mediastinal pancreas

Pancreatic ectopia in the mediastinum is rare, and there are no reports that it has ever given rise to malignancy. Here we report a case of adenocarcinoma arising in ectopic pancreatic tissue in the mediastinum of a 66-year-old woman. The tumor arose in a partially cystic and partially solid ectopic pancreas containing both exocrine and endocrine components. Thorough clinical examination and clinical follow-up did not reveal other primary sites. The tumor was partially resected but metastasized to the anterior sternum 6 months later and was re-excised. No other similar cases of primary mediastinal pancreatic adenocarcinoma are on record in medical literature.     

Hibernoma: a report of 2 unusual cases with a review of the literature

Hibernomas are rare neoplasms composed of brown adipose tissue. The behavior of these neoplasms has been described as uniformly benign in humans. The only recurrence cited in the English literature involved a sarcoma with hibernoma-like features, which was reported in abstract form. We present 2 cases of hibernoma, one that continued to grow following partial excision and another at an unusual site (anterior abdominal wall). Both of these tumors overexpressed p53 protein by immunohistochemistry, which was a novel finding. A review of the literature highlights recent advances that may help confirm the diagnosis and explain the biology of these rare tumors.     

Mesothelial cell inclusions within mediastinal lymph nodes

The presence of mesothelial cell inclusions within mediastinal lymph nodes is an extremely rare occurrence with apparently only two previously reported cases. We report a single case with immunohistochemistry and transmission electron microscopy. A study of 318 mediastinal nodes from 80 patients using haematoxylin and eosin and immunohistochemistry is reported with the observation of no further positive cases. A review of the literature concerning nodal inclusions found at other anatomical sites aids discussion on the aetiology of this type of nodal inclusion.     

Extramedullary myeloid cell tumours localised to the mediastinum: a rare clinicopathological entity with unique karyotypic features

Extramedullary myeloid cell tumour (EMMT) localised to the mediastinum is a rare manifestation of acute myeloid leukaemia, forming less than 4% of all cases of EMMT. In contrast to other types of EMMT, cytogenetic characteristics of this rare entity are relatively unknown. This report describes a patient with EMMT who had evidence of superior vena cava syndrome and normal peripheral blood counts at diagnosis. The results from an initial biopsy specimen were consistent with a diagnosis of mediastinal large B cell lymphoma. A diagnosis of acute myeloid leukaemia was made three months after initial diagnosis by bone marrow examination. Review of the initial biopsy specimen showed strong positivity for myeloperoxidase, revealing that the patient had been initially misdiagnosed as having large B cell lymphoma. Cytogenetic studies revealed a near triploid and near tetraploid karyotype with structural abnormalities in 12 and three metaphases, respectively. Review of the literature showed that a near tetraploid or triploid karyotype is found in most of the reported cases of mediastinal EMMT. Thus, the presence of a near triploid/tetraploid karyotype and mediastinal EMMT may represent a specific subset of EMMT. The biological relevance of this observation is discussed.     

Neuroendocrine carcinoma in a mediastinal teratoma as a rare variant of somatic-type malignancy

Somatic-type malignancy (STM), defined as any sarcoma, carcinoma, leukemia or lymphoma developing in a germ cell tumor, occurs in approximately 2 % of all germ cell tumors. Neuroendocrine carcinoma developing in a mediastinal germ cell tumor has not been previously reported. We here describe a 22-year-old man who underwent resection of a 11-cm mediastinal teratoma which consisted of components of all three germ cell layers with prominent foci of fetal-like liver tissue. The liver areas were surrounded by primitive neuroendocrine structures with ductal and solid growth pattern with a high proliferation rate. We diagnosed an immature mediastinal teratoma with STM, specifically neuroendocrine carcinoma arising in a background of immature liver tissue. Comparative genomic hybridization of dissected tumor tissue revealed chromosomal gains at 12 in the teratoma and neuroendocrine carcinoma component. In summary, clinicians and pathologists should be aware of neuroendocrine carcinoma as a rare type of STM complicating mediastinal germ cell tumors.     

Pharmacological effects of nicotine on norepinephrine metabolism in rat brown adipose tissue: relevance to nicotinic therapies for smoking cessation

In a two-year carcinogenicity study with administration of high doses of the partial nicotinic agonist varenicline (recently approved for smoking cessation), mediastinal hibernomas occurred in three male rats. To investigate potential mechanisms for partial and full nicotinic agonists to contribute to development of hibernomas, the effects of nicotine on rat brown adipose tissue (BAT) were studied. Male and female rats were administered nicotine at doses of 0, 0.3, and 1 mg/kg subcutaneously for fourteen days. Intrathoracic (mediastinal periaortic and mediastinal perithymic) BAT and interscapular BAT were examined microscopically, and determinations of uncoupling protein-1 (UCP-1) expression and norepinephrine (NE) content were made. Additionally, NE turnover was measured in mediastinal periaortic and perithymic BAT. Nicotine (1 mg/kg) administration resulted in decreased vacuolation only in mediastinal periaortic and mediastinal perithymic BAT of males and elevated UCP-1 in mediastinal periaortic BAT of males and females. Increased NE content occurred only in mediastinal periaortic BAT of males given 0.3 and 1 mg/kg doses, whereas NE turnover was decreased in both males and females given 1 mg/kg. Together, these data demonstrate that nicotine primarily affects mediastinal BAT in male rats, consistent with the gender and location of the hibernomas observed in the two-year carcinogenicity study.     

Benign thymic lesions: a practical approach to microscopic differential diagnosis

Histopathologic differential diagnosis of benign thymic lesions requires consideration of many benign and malignant mediastinal diseases. True thymic hyperplasia and follicular thymic hyperplasia, and especially LESA-like thymic hyperplasia most often require differentiation from lymphomas (usually MALT lymphoma) or thymomas (usually B1/B2 type or micronodular thymoma with lymphoid stroma). Thymic cysts are relatively common, but not all are resected and examined microscopically. Unilocular cysts most often need to be differentiated from pericardial or foregut cysts or lymphoid malformations. Multilocular cysts need to be primarily distinguished from teratoma. Some thymomas can also present as cysts. Thymolipomas, tumors with an intriguing morphology and unclear etiology, can cause particular difficulty because they are very rare and morphologically heterogeneous; they may resemble thymoma infiltrating adipose tissue. Of great importance in establishing the correct diagnosis in many cases are immunohistochemical tests and also radiological findings in chest CT/MRI, which allows determination of the exact location of the lesions, their multiplicity, structure and nature of growth. The most important thymic/mediastinal diseases discussed in this review are illustrated with CT/MRI scans and microscopic images, highlighting morphologic features and immunohistochemical results that are important in the differential diagnosis.     

Acute mediastinitis,mediastinal granuloma,and chronic fibrosing mediastinitis: A review

Acute mediastinitis is a rare infection that carries high morbidity and mortality. They are complications seen most often with deep sternal wound infections from surgeries with median sternotomies, oropharyngeal and odontogenic infections and esophageal perforations. These conditions should be promptly recognized and treated. Mediastinal granulomas are focal, mass-like lesions commonly resulting from prior granulomatous infections. They are regarded as benign, self-resolving lesions however can cause complications by compression of adjacent mediastinal structures. Chronic fibrosing mediastinitis is a rare, diffuse fibroinflammatory process most often seen with granulomatous infections and carries a worse prognosis than mediastinal granulomas especially when adjacent mediastinal structures are compromised. In this review, we discuss the epidemiology, etiology, clinical presentation, treatment and prognosis of acute mediastinitis, mediastinal granulomas, and chronic fibrosing mediastinitis.     

Germ-cell tumors of the mediastinum.

Mediastinal germ-cell tumors (GCTs) usually occur within the anterior mediastinum, accounting for about 15% of all mediastinal cysts and tumors. They are associated with the thymus, presumably arising from extragonadal germ cells or thymic cells with germ-cell potential. Mediastinal seminoma develops primarily in young males with rare cases reported in females; likewise, embryonal carcinoma, endodermal sinus tumor or yolk-sac tumor, choriocarcinoma, and malignant mixed or combined GCTs also overwhelmingly affect males. Mature cystic teratoma affects males and females equally. The prognosis for mediastinal mature cystic teratoma and seminoma is very good. Nonseminomatous malignant GCTs of the mediastinum often present with advanced disease and do not respond as well to chemotherapy as their gonadal counterparts. Nonetheless, it is important to separate mediastinal GCTs from other undifferentiated malignant tumors, especially thymic carcinoma, which has a poor prognosis. Clearly, some patients with mediastinal GCTs respond very well to modern therapies.     

Ossifying fibromyxoid tumour of soft parts: report of four cases including one mediastinal and one infantile

Four cases of ossifying fibromyxoid tumour of soft parts are described. One of them was in the mediastinum, a hitherto unreported location of this rare neoplasm. Another was removed from the subcutaneous tissue of the head of a two-year-old girl, the youngest patient so far described. A peculiar feature of this tumour was haphazard spindle cell groups showing smooth muscle differentiation. One tumour was remarkably proliferative with 20 mitotic figures per 10 high power fields and 50% of cells positive for Ki-67 antigen. Immunohistochemical analysis revealed that all the tumours were diffusely positive for vimentin, and focally for S-100-protein. In addition to this the infantile tumour expressed focal alpha-smooth muscle actin, desmin and glial fibrillary acidic protein, while the mediastinal tumour expressed only alpha-smooth muscle actin and the highly proliferative one expressed none of these antigens. Background cells, including histiocytes, lymphocytes and mast cells were numerous. DNA cytometry analysis using both static and flow methods showed that the mediastinal tumour contained two cell clones, while the others were diploid. The proliferative fraction of cells (S plus G2 phases) was prominent in the proliferative and infantile tumours.     

Carcinoid tumor arising in a thymic bronchogenic cyst associated with thymic follicular hyperplasia

Bronchogenic cysts are congenital malformations of the embryonic tracheobronchial tree and are the most common cause of mediastinal cysts, encountered mainly in pediatric patients and young adults. Conservative treatment has been proposed for asymptomatic patients. However, malignant transformation occurs occasionally and the clinicopathological features of secondary malignancy are not well characterized. In this report, we present a carcinoid tumor found in the thymic bronchogenic cyst of a 41-year-old female complaining of mild chest pain. The thymic tissue also shows follicular lymphoid hyperplasia. Atypical imaging features were found in her chest computed tomography. Additional 22 cases of bronchogenic cysts with malignant transformation were also reviewed from the literature. The clinicopathological data were summarized. The tumorigenesis of these tumors is unclear, but bronchogenic cysts of the lung may undergo malignant changes at a younger patient age and more frequently than mediastinal ones. Carcinoid tumors were also seemingly overrepresented in mediastinal cases. Some atypical imaging features may serve as clues for early detection and guide clinical management.