Cutaneous lipomatous neoplasms.

Benign and malignant lipomatous tumors are the most common neoplasms of subcutaneous and deep soft tissues in adults. In contrast, purely cutaneous lipogenic neoplasms are exceptionally rare, and some entities and variants of adipocytic neoplasms have not yet been described in the skin. In addition, some dermal lipogenic neoplasms are characterized by different specific clinicopathologic features in comparison with more deeply located tumors. Cutaneous angiolipoleiomyoma ("angiomyolipoma") is seen most often in male patients and in an acral location. It is characterized histologically by mature adipocytes, thick-walled blood vessels, and smooth muscle cells arranged in well-defined fascicles and around blood vessels. Smooth muscle cells in cutaneous angiolipoleiomyoma stain negatively for HMB-45, in contrast to renal and extrarenal angiomyolipoma. Adenolipoma of the skin is a superficially located form of lipoma composed of large lobules of mature adipocytic tissue admixed with eccrine ducts and glands. Cutaneous spindle cell/pleomorphic lipomas, in contrast to subcutaneous forms, are more common in female patients and have a wide anatomic distribution. Histologically, cutaneous spindle cell/pleomorphic lipomas are characterized by an infiltrative growth pattern mimicking more aggressive lesions. Rarely, liposarcoma may occur as a purely cutaneous lesion with a favorable clinical prognosis despite high-grade morphologic features in many cases.     

Atypical lipomatous hamartoma of the lung

Summary An unusual lipomatous tumour discovered accidentally in the right middle lobe of a 34-year old woman is described. The tumour was associated with an intrapulmonary typical chondromatous hamartoma in the same lobe but separate from the first lesion.The lipomatous tumour was primarily an intrapulmonary lipoma but in a few of the numerous sections made minute islands of cartilage and bone were discovered along with a few epithelial-lined clefts. These justify the diagnosis of a lipomatous hamartoma.Dispersed among the mature fat cells were a few immature cells with atypical nuclei. Cellular atypia in predominantly lipomatous hamartomas has not previously been reported. As the occurrence of atypical lipoblast-like cells might lead to an erroneous diagnosis of liposarcoma, this case is thought worthy of reporting.     

Intramedullary lipomatous ependymoma: case report

A 51 year-old man was admitted to our hospital with poor general health and neurological disturbances with paresthesia, dysuria and defecation disorder. Neuroimaging showed a syringomyelia cyst from C1 to conus medullaris, together with a intramedullar tumoral mass in T6-T7. Histological examination of the surgical specimen led to the diagnosis of lipomatous ependymoma.     

Retroperitonial atypical lipomatous tumour--a case report

We report a case of atypical lipomatous tumor-sclerosing type, a rare retroperitoneal soft tissue liposarcoma, presented with vague musculoskeletal symptoms. Patient was managed with complete resection of the tumor mass with adjuvant chemotherapy. The patient is doing well, with no evidence of recurrence 22 months after the treatment.     

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.     

Well-differentiated liposarcoma (atypical lipomatous tumors).

Well-differentiated (WD) liposarcoma accounts for about 40% to 45% of all liposarcomas therefore representing the larger subgroup of adipocytic malignancies. It tends to occur equally in the retroperitoneum or the limbs followed by the paratesticular area and the mediastinum, with a peak incidence between the fifth and the seventh decades. WD liposarcoma is further subdivided in the adipocytic (lipoma-like), sclerosing, inflammatory, and spindle cell subtypes, of which the first two are by far the commoner. WD adipocytic liposarcoma is composed of a relatively mature adipocytic proliferation, featuring cell size variation as well as at least focal nuclear atypia. A varying number (from many to none) of lipoblasts may be found. Sclerosing WD liposarcoma is characterized microscopically by the presence of scattered distinctive bizarre stromal cells and multivacuolated lipoblasts set in a fibrillary collagenous background. Inflammatory liposarcoma represents a rare variant of WD liposarcoma in which a chronic inflammatory infiltrate predominates to the extent that the differential diagnosis is mainly with nonadipocytic lesions such as inflammatory myofibroblastic tumor, Castleman's disease, and Hodgkin's as well as non-Hodgkin's lymphomas. Spindle cell liposarcoma is the rarest variant and is composed neural-like spindle cell proliferation set in a fibrous and/or myxoid background and associated with an atypical lipomatous component which usually includes lipoblasts. Cytogenetically, WD liposarcoma appears to be relatively homogenous exhibiting characteristic ring as well as giant marker chromosomes containing amplified genetic material derived from the 12q13-15 chromosome region. As WD liposarcomas of any type have no potential for metastasis unless they undergo dedifferentiation, the opportunity to replace the term "WD liposarcoma" with a less frightening denomination has produced a long, sharp debate. WD liposarcoma and atypical lipoma should be considered as synonyms and their use should therefore be determined by the degree of reciprocal comprehension between the surgeon and the pathologist to prevent either inadequate or excessive treatment.     

Recurrent haemosiderotic fibrohistiocytic lipomatous lesion of the hand

Haemosiderotic fibrohistiocytic lipomatous lesion (HFLL) is a rare lesion, with uncertain aetiology, occurring almost predominantly in the lower limb. The lesion is known to recur locally in the foot and ankle region. We report a recurrent HFLL affecting the hand in a 55-year-old female, after excision of a soft tissue swelling in the same location 2 years previously. There was no history of trauma and the histological appearances of the original and recurrent lesions were almost identical, favouring a neoplastic nature of HFLL.     

Extensive lipomatous metaplasia in bilateral macronodular adrenocortical hyperplasia

OBJECTIVE: We describe a case of macronodular hyperplasia with marked adrenal enlargement in which mature adipose tissue was a significant component. To our knowledge, this condition has not been reported previously. METHODS: A 42-year-old woman with newly diagnosed Cushing's syndrome underwent endoscopic bilateral adrenalectomy to remove bilateral adrenal masses. RESULTS: Both adrenal glands displayed features of macronodular hyperplasia with marked adrenal enlargement, and abundant mature adipose tissue was identified in some nodules of both glands. CONCLUSIONS: Lipomatous metaplasia is histologically demonstrated in a case of macronodular hyperplasia with marked adrenal enlargement. This distinctive change may be secondary to metaplastic transformation of either stromal cells or adrenocortical cells. The presence of lipomatous metaplasia would appear to indicate adrenocortical process, since, to our knowledge, it has never before been described in the adrenal nodule.     

Squamous cell carcinoma and lipomatous pseudohypertrophy of the pancreas

 A 68-year-old woman who had been treated for non-insulin-dependent diabetes mellitus for the past 20 years was admitted to hospital because of abdominal pain and weight loss. Radiological investigation revealed a tumour in the body of the pancreas and numerous intraductal calcifications in both the tail and the head of the pancreas. Left-sided pancreatectomy was performed to remove the tumour. The resection specimen showed fatty enlargement of the parenchyma and numerous intraductal calcifications in the tissue adjacent to the tumour, which was 7 cm in diameter and was found to be a primary squamous cell carcinoma with a spindle cell component. There was also lipomatous pseudohypertrophy. Received: 24 September 1998 / Accepted: 15 February 1999     

Genetic investigation for the differential diagnosis of lipomatous tumors

Summary Adipose tissue tumors are often characterized by typical or even specific chromosomal alterations. In some of the cases the molecular background of these microscopically visible alterations was already elucidated. In myxoid liposarcomas the translocation t(12;16) creates a fusion gene between the CHOP gene and the FUS gene and in lipomas the HMGI-C gene becomes rearrranged by structural aberrations involving chromosomal region 12q14–15. Based on examples of a lipoma, a well-differentiated liposarcoma, a myxoid liposarcoma, and an aggressive angiomyxoma it is demonstrated in the present paper how cytogenetic investigation can be used as an additional tool for an improved diagnosis of adipose tissue tumors. Furthermore, the detection of molecular mechanisms underlying the visible cytogenetic alterations will certainly significantly increase our knowledge about the pathogenesis of these diseases.      

Hemosiderotic fibrohistiocytic lipomatous lesion: clinical correlation with venous stasis

Hemosiderotic fibrohistiocytic lipomatous lesion (HFLL) is a recently proposed lipomatous entity. HFLL was originally suggested to be a benign reactive lesion arising due to an antecedent trauma. We report two patients with HFLL who also suffered from chronic vein insufficiency due to varicose involving deep veins of the low limbs. Both patients were middle-aged women with solitary, poorly circumscribed subcutaneous lesions on the lower extremities. Histopathological examination revealed typical features of HFLL. We think that the consistent clinical features such as advanced age, female sex predilection, and specific location along with distinctive histopathological features allow the suggestion that impaired blood circulation, to wit, venous stasis is involved in the pathogenesis of HFLL. We hypothesize that the proliferation of spindled fibroblastic and myofibroblastic cells and capillaries, erythrocyte extravasation, and hemosiderin deposition with lipomatous tissue of HFLL may simply represent an exaggerated tissue response to venous stasis in which elevated venous and capillary pressures, oxygen saturation, and edema stimulate the proliferation of the abovementioned elements and lead to erythrocyte extravasation. A similar histopathological pattern is seen in acroangiodermatitis of Mali and vascular transformation of lymph node sinuses, and these conditions are also associated with impaired blood circulation.     

A case of myxoid adrenocortical carcinoma with extensive lipomatous metaplasia

We report a combination of unusual myxoid change and extensive lipomatous metaplasia of an adrenocortical carcinoma. The patient was a 38-year-old man with hypertension and heart failure. Radiographic examination revealed the presence of a left adrenal tumor, and adrenalectomy was performed. The tumor weighed 380 g and appeared encapsulated. The cut surface was predominantly gelatinous. Histologically, the tumor was composed of atypical round cells with eosinophilic to vacuolated cytoplasm. The tumor was diagnosed as adrenocortical carcinoma. The stroma accumulated copious mucinous material. In addition, individual to nodular mature adipocytes were admixed throughout the tumor. The transition from carcinoma cells to mature adipocytes was recognized. Myxoid change is a very rare phenomenon in adrenocortical carcinoma, and only 10 similar cases have been reported to date. Lipomatous metaplasia is another peculiar feature of adrenocortical lesions that has been reported only in benign conditions. To our knowledge, this is the first reported case of adrenocortical carcinoma with lipomatous metaplasia.     

Retroperitoneal lipomatous angiomyolipoma associated with amyloid deposition masquerading as well-differentiated liposarcoma

Reported herein is a case of retroperitoneal angiomyolipoma associated with amyloid deposition, masquerading as well-differentiated liposarcoma. A 16 x 13 cm lipomatous tumor was resected from the perirenal retroperitoneum of a 71-year-old woman. Microscopically, the tumor was exclusively composed of mature adipose tissue and abnormal thick blood vessels, but bundles of smooth muscle were lacking. In addition, amyloid was deposited between fat cells. Initially, well-differentiated liposarcoma was highly suspected. However, there were a few epithelioid cells with clear vacuolated cytoplasm within the vessel walls, which were immunoreactive for smooth muscle markers and HMB-45. Real-time polymerase chain reaction failed to demonstrate the amplification of the murine double-minute type 2 gene and cyclin-dependent kinase 4 gene in this tumor. Therefore, the tumor was diagnosed as lipomatous angiomyolipoma. After the diagnosis, it was found that the patient had multiple myeloma and cardiac amyloidosis, suggesting that the amyloid deposition within the tumor was a complication of the myeloma. Lipomatous angiomyolipoma may be a diagnostic pitfall of retroperitoneal lipomatous tumors.