Case Study An interesting case of Anterior Mediastinal mass Shyamala.K.K1, S.Sreenivasa Rao2, S.Mahesh Babu3, Mona Sepehrar4 1,2 Dr.B.R.Ambedkar Medical College, 3 KS.Hegde MC, 4Baptist Hospital, Karnataka, India. Email:
[email protected] International Journal of Clinical Cases and Investigations. Volume 6 (Issue 3), 38:42, 1st April 2015. Abstract Lipoma of the anterior mediastinum is rare and constitutes about 1.6%–2.3% of all primary mediastinal tumors. We report Anterior Mediastinal Lipoma in a 55 year old female patient admitted with Pain abdomen and was operated for intestinal obstruction. Patient complained of facial puffiness in early morning after getting up from sleep, intermittent hoarseness of voice and difficulty in swallowing. Clinical examination was normal except for sinus tachycardia. Upper GI endoscopy was normal. Laboratory investigations are normal except for Dyslipidemia. Chest radiography showed homogenous opacity involving the middle zone and lower zone on right side with well defined margins and lobulated margins superiorly. CT scan of chest showed a large, hypodense mass lesion in the anterior mediastinum having low attenuation of about 100HU. CT guided FNAC and biopsy confirmed diagnosis of Lipoma. Lipoma in mediastinum is an incidental finding in Radiography. Massive Lipoma can cause compression of adjacent structures including lungs and Superior venacava. All patients with Mediastinal Lipoma should be evaluated to rule out Liposarcoma and to be differentiated from mediastinal lipomatosis and Thymolipoma. Keywords: Anterior Mediastinum, Lipoma/complications, Mediastinal Neoplasms Introduction: Lipomas are common benign soft tissue tumor composed of adipose tissue.1 Commonly found in adults from 40 to 60 years of age, but can occur in all ages. Approximately one percent of the general population has a lipoma.2 Lipomas are usually relatively small with diameters of about 1–3 cm but can attain large sizes.3 In intestine, lipomas constitute 16% of benign, small neoplasms; i.e., less than leiomyomas (18%) and more than adenomas (14%).
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Exact etiology of lipoma is not known. Gene rearrangements of chromosome 12 association was established in solitary lipomas, with abnormality in HMGA2-LPP fusion gene.4 Lipomas of anterior mediastinum approximately represent 1.6%–2.3% of all primary mediastinal tumors.5 Case Report: A 55 year old female patient was admitted in surgical ward with complaints of pain abdomen in Right upper and lower quadrants and also epigastric region from a period of 10 days. History revealed that she is a housewife by occupation and diagnosed with Diabetes mellitus since 2 years. Patient was non-specifically sick since 10 days with nausea, vomiting and pain abdomen. Patient complained of pain in right lower and upper quadrant of abdomen which aggravated over a period of 5 days. Patient was diagnosed to have intestinal obstruction and emergency surgery was performed. History from patient also revealed that patient had history of facial puffiness in the early mornings after getting up from sleep which is intermittent. She also complained of intermittent hoarseness of voice and difficulty of swallowing since 15 days. No other significant history was revealed. Clinical examination revealed that patient is obese with BMI of 34 and has Tachycardia(Heart rate: 106/min) and BP of 110/70 mm Hg. Abdominal examination showed tenderness in right hypochondrium and lumbar regions along with epigastric tenderness. Other systemic examination was normal. Electrocardiogram of patient showed tachycardia. Laboratory findings were as follows: total white blood cell count of 11,100 /mm3, Hemoglobin of 12mg/dl and platelet count was 199,000. The arterial blood gas analysis was normal. Renal function test was normal with Creatinine of 1.1mg/dl and Blood urea of 30mg/dl. Liver function test and Thyroid profile was normal. Lipid profile was abnormal (low density lipoprotein (LDL): 366 mg/dL, triglyceride (TG): 362 mg/dL, high density lipoprotein (HDL): 40 mg/dL, HbA1C: 7.9%). Chest radiography showed homogenous opacity involving the middle zone and lower zone on right side with well defined margins and lobulated margins superiorly. Computerized Tomography of chest showed a large, hypodense mass lesion in the anterior mediastinum having low attenuation measuring 3 × 5 cm, ending above the area of the right atrium, extra pericardial in appearance causing partial collapse of lung. CT guided FNAC and biopsy confirmed diagnosis of Lipoma. Patient refused surgery for removal of lipoma.
Discussion: In mediastinal mass lesions, mesenchymal tumors constitute about 6%. In the mediastinum, lipomas are commonly found in the anterior mediastinum. Even with large size, lipomas uncommonly produce symptoms.6 In one case report by Jack and co-workers,7 large intrathoracic lipoma was reported that impaired left ventricular function by direct compression. Their patient expired after refusing surgery due to compression.
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Lipomas contain fibrous, incomplete septa which separate the sheets of mature adipocytes histologically. Review of literature by John Politis et al indicated 5 groups of intrathoracic lipoma, i.e., endobronchial, parenchymal, pleural, mediastinal and cardiac. Lipoma should be differentiated from Liposarcoma as the prognosis is poor and growth of tumor is rapid.8 Low grade malignancy poses a diagnostic challenge especially in well differentiated form. Liposarcoma usually have varying adipocytes size with eosinophilic cytoplasm and hyperchromatic nuclei. CT scan can differentiate Lipoma from undifferentiated Liposarcoma due to better enhancement and density of mass. Fatty necrosis is seen in 25% of Liposarcoma.9 Lipoma should also be differentiated from mediastinal lipomatosis, characterized by accumulation of fat seen in Cushing’s syndrome and chronic corticosteroids usage. Another benign, slow growing neoplasm of the mediastinum is Thymolipoma which can be differentiated with histology. Complete excision of mass is the procedure of choice diagnostically and therapeutically if possible to excise completely. If complete excision cannot be done, surgery is not preferred as it increases chances of recurrence.10 Conclusion: Mediastinal lipomas are rare tumors incidentally found in radiography as in our patient. Lipoma can cause compression of Lungs causing collapse, adjacent cardiac structures including Superior Vena cava causing symptoms which is rarely reported is found in our patient. Mediastinal lipomas should be differentiated from mediastinal lipomatosis, Thymolipoma and especially Liposarcoma as prognosis is poor. CT scan is the investigation of choice and complete resection is the treatment of choice if feasible. References: 1. Bancroft LW, Kransdorf MJ, Peterson JJ, O'Connor MI (October 2006). "Benign fatty tumors: classification, clinical course, imaging appearance, and treatment". Skeletal Radiol. 35 (10): 719–33. doi:10.1007/s00256-006-0189-y. PMID 16927086. 2. M. J. Kransdorf, “Benign soft-tissue tumors in a large referral population: Distribution of specific diagnoses by age, sex, and location,” American Journal of Roentgenology, vol. 164, no. 2, pp. 395–402, 1995. 3. Hakim E, Kolander Y, Meller Y, Moses M, Sagi A (August 1994). "Gigantic lipomas". Plast. Reconstr. Surg. 94 (2): 369–71. doi:10.1097/00006534199408000-00025. PMID 8041830. 4. Italiano A, Ebran N, Attias R, et al. NFIB rearrangement in superficial, retroperitoneal, and colonic lipomas with aberrations involving chromosome band 9p22. Genes Chromosomes Cancer. Nov 2008;47(11):971-7. 5. Gaerte SC, Meyer CA, Winer-Muram HT, Tarver RD, Conces DJ: Fat-containing lesions of the chest. Radiographics 2002, 22:61-78. 6. Rubush JL, Gardner IR, Boyd WC, Ehrenhaft JL. Mediastinal tumors. Review of 186 cases. J Thorac Cardiovasc Surg 1973;65:216–22. 7. Jack AI, Blohm ME, Lye M. An intrathoracic lipoma impairing left ventricular function. Br Heart J 1995;74:95.
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8. Primary Sarcomas Of The Mediastinum: Results Of Therapy Burt, Michael et al. The Journal of Thoracic and Cardiovascular Surgery , Volume 115 , Issue 3 , 671 - 680 9. Weiss SW, Enzinger GoldblumJR: Lipomatous Tumours. In Histological Typing of Soft Tissue Tumours. St. Louis, MO: Springer; 1994:23-26. 10. Kato M, Saji S, Kunieda K, Yasue T, Nishio K, Adachi M(1997) Mediastinal lipoma: report of a case. Surg Today 27:766–768.
Figures
Figure 1: Chest Radiograph of patient showing Right middle and lower zone opacity
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Figure 2: Computerized Tomography of Thorax showing Anterior Mediastinal mass
Figure 3: Fine needle aspiration cytology of patient showing lipoma
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