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Introduction: Lipoma is the most frequent benign tumor of the soft tissue. This lesion is often asymptomatic except in cases of enormous masses compressing nervous-vascular structures. Although the diagnosis is mostly clinical, imaging tools are useful to confirm the adipose nature of the lesion and to define its anatomic border. Sometimes, lipomas may be the result of a previous trauma, such as in this patient., Case Presentation: A 45-year-old man presented at our institution with a giant hard firm mass in the upper external quadrant of the right buttock disclosed after a weight loss diet. Subsequent magnetic resonance imaging showed a giant adipose mass developed beneath the large gluteal muscle and among the fibers of the medium and small gluteal muscles. When questioned on his medical history, the patient reported a blunt trauma of the lower back 14 years earlier. He underwent surgery and histological examination confirmed a giant lipoma., Conclusion: Lipomas might result from a previous trauma. It is hypothesized that the trigger mechanism is activated by cytokine and growth factors released after the trauma. We herein present an exceptional case of a giant post-traumatic lipoma which caused a painful compression on the right sciatic nerve.

Background: Gastrointestinal stromal tumors (GIST) of the stomach are the most frequent followed by those of the intestinal tract, while colon and rectum represent rare sites. GIST of the anal canal are extremely rare. They have been studied along with GIST of the rectum, as a single entity, and along with them they represent 5% of GIST. GIST arising from the anal canal account for only 2%-8% of the anorectal GIST. Thus anal GIST must be considered an exceptional case., Case Presentation: A 78-year-old man was referred to our Institution for an anal mass, in absence of any symptom. The patient was treated by local excision. An histological diagnosis of a low grade GIST was made. No further treatment was necessary. No local recurrence of distant metastases were found at follow-up., Conclusion: At the moment, only ten cases of c-kit positive anal GIST are reported in the literature. These few data are not sufficient to establish a widely accepted approach for this neoplasia. We recommend to perform an initial local excision, to define the risk of aggressive behavior and the resection margins and proceed to a more aggressive treatment, if the GIST belongs to high or very high risk group. The role of adjuvant therapy is still uncertain. Although inhibitors of tyrosine-kinase receptor needs further studies before their routine use, their role in case of distant or local recurrence has been accepted. Patients' close follow up is mandatory to disclose as soon as possible local recurrences or metastases.

Background: Biliary cystadenoma is a rare benign neoplasm, which is often misdiagnosed for a hepatic abscess or a hydatid cyst that tends to recur and is at risk for progression to malignant neoplasm., Case Presentation: This case describes a 30-year-old woman admitted to our institution in an emergency setting. The patient was originally misdiagnosed as affected by a hepatic hydatid cyst at another hospital, and then emergently treated at our Institution for severe abdominal pain. Histologic evaluation of the cyst showed that it was a biliary cystadenoma and, therefore, the patient underwent a hepatic resection in order to completely remove the lesion., Conclusion: Complete excision of any suspicious hepatic cystic lesion remains the best method for diagnosis and treatment of cystadenoma. Incomplete excision of most biliary cystadenoma results in a higher rate of recurrence and the risk of malignant transformation. We report this case to elucidate the clinical presentation, preoperative evaluation, and surgical treatment of these rare lesions.

Background: Hepatocellular adenomas are the most common benign liver tumors. They are usually related to oral contraceptive intake., Case Presentation: This case describes a 58-year-old woman admitted to our institution for a hepatic mass incidentally discovered during a routine examination. The patient, who was never on oral contraceptives, was asymptomatic upon admission. She underwent a thorough diagnostic evaluation and then a hepatic right trisegmentectomy. The histologic evaluation of the mass showed that it was a hepatocellular adenoma with areas of bone marrow metaplasia., Conclusion: Bone marrow metaplasia has rarely been found associated to liver tumors. The presence of marrow-derived hepatic progenitor cells might be the source of both adenoma hepatocytes and bone marrow differentiated cells. To our knowledge, this is only the second case in the English literature in which areas of bone marrow metaplasia were found in a hepatocellular adenoma.