Diagnosis of thymolipoma with fine needle aspiration biopsy. Report of a case initially misdiagnosed as liposarcoma.
BACKGROUND
Thymolipomas are the most outstanding mesenchymal mediastinal tumors although they represent only a small percentage of thymic neoplasms. Their histogenesis remains unsolved, and they are usually benign. Fine needle aspiration biopsy (FNAB) has become the method of choice for the study of mediastinal tumors, including thymolipomas. Making the correct diagnosis depends on the availability of all thymic and lipomatous components as well as on the correct application of a differential diagnosis with other lipomatous tumors.


METHODS
A 24-year-old woman had a 3-month history of coughing with sputum, fever, asthenia, adynamia, headaches and anemia. Physical examination revealed a bilateral pulmonary condensation syndrome. Imaging studies showed a well-defined, large mass occupying both hemithoraxes and the mediastinum. FNAB revealed an admixture of atypical adipocytes, nonneoplasic lymphoid tissue and capillaries with prominent endothelium. An initial diagnosis of well-differentiated liposarcoma was made. A 2.8-kg, encapsulated, yellowish gray mediastinal tumor was surgically removed. Mature adipose tissue intermingled with abundant thymic tissue containing numerous Hassall's corpuscles were seen histologically. Immunohistochemical markers for thymic epithelium, lymphoid tissue and adipocytes were all positive. Thymolipoma was the final diagnosis. The anemia subsided with resection of the tumor, and the patient was disease free 2.5 years after surgery.


CONCLUSIONS
To the best of our knowledge, this is the second report of a thymolipoma studied with FNAB. The criteria for the differential diagnosis between thymolipomas and other lipomatous tumours should be kept in mind.
Romero-Guadarrama
Mónica Belinda
MB
Servicio de Patología, Hospital General de México, Dr. Balmis No. 148, Col. Doctores, Del. Cuauhtémoc, C.P. 06726, México, D.F. Mexico. monicaromero@att.net.mx
Durán-Padilla
Marco A
MA
Cruz-Ortíz
Humberto
H
Castro-Gómez
Lisset
L
López-Vancell
Dolores
D
Novelo-Retana
Virginia
V
Santiago-Prieto
Ana Cecilia
AC
Fierro-Chávez
Erika
E
Rodríguez-Martínez
Héctor A
HA
D000328:Adult; D018951:Antigens, CD20 / Q000032:analysis; D044963:Biopsy, Fine-Needle; D002272:Carcinoembryonic Antigen / Q000032:analysis; D003951:Diagnostic Errors; D005260:Female; D006801:Humans; D016130:Immunophenotyping; D007633:Keratins / Q000032:analysis; D017493:Leukocyte Common Antigens / Q000032:analysis; D008067:Lipoma / Q000473:pathology*; D008080:Liposarcoma / Q000175:diagnosis*; D008279:Magnetic Resonance Imaging; D008479:Mediastinal Neoplasms / Q000473:pathology*; D010503:Periodic Acid-Schiff Reaction; D013902:Radiography, Thoracic; D009418:S100 Proteins / Q000032:analysis; D013934:Thymectomy; D013953:Thymus Neoplasms / Q000175:diagnosis* / Q000000981:diagnostic imaging / Q000473:pathology / Q000601:surgery; D014057:Tomography, X-Ray Computed; D014746:Vimentin / Q000032:analysis
D018951:Antigens, CD20; D002272:Carcinoembryonic Antigen; D009418:S100 Proteins; D014746:Vimentin; D007633:Keratins; D017493:Leukocyte Common Antigens