Medical Image of the Month: Thymolipoma

Figure 1. Chest radiograph PA view revealing subtle prominence of left upper heart border (white arrow).

Figure 2. CT Topogram: The prominence of left heart border is discretely seen suggesting pliability of the lesion (due to supine position).

Figure 3. CECT axial and coronal images revealing a fat containing anterior mediastinal mass with strands of soft tissues (HU values as depicted in image).

Figure 4. CECT of the thorax one year after resection: post contrast image revealing no mediastinal mass lesion.

A 20-year-old man presented with a continuous, mild, dull aching pain affecting the left chest pain for 15 days duration. There were no aggravating or relieving factors nor any history of fever, respiratory or cardiac symptoms. The patient’s vital signs were normal and examination of the respiratory and the cardiovascular systems revealed no abnormality. Electrocardiography and biochemical investigations, including cardiac enzymes, were normal. Chest radiography (Figure 1) revealed a subtle opacity causing fullness of the aorto-pulmonary window with subtle, smooth prominence of the left upper cardiac border; the left hilum was visualised discretely through the opacity (Figure 2). The patient underwent enhanced contrast chest CT (CECT, Figure 3) for further evaluation, revealing a large mass measuring 13 x 7.9 x 5 cm in the anterior mediastinum, extending from thoracic inlet to the left cardiophrenic angle. The mass consisted predominantly of fat density, with an average attenuation of - 84 Hounsfield units (HU). Non-enhancing strands of soft tissue foci (mean, 32 HU) were also seen within the lesion. No areas of calcification or cystic degeneration were present. Planes between the subjacent mediastinal structures were preserved (Figures 2 and 3). A radiological impression of thymolipoma was offered. The patient was transferred to a tertiary care center where he underwent thoracoscopic excision and histopathology confirmed thymolipoma. Following surgery, the patient recovered uneventfully and follow up chest radiography and enhanced contrast chest CT (Figure 4) showed no evidence of lesion recurrence.

Thymolipoma is a rare benign tumor originating in the anterior mediastinum, and comprises 2-9% of all thymic neoplasms (1). Cytogenetic analyses have demonstrated that thymolipoma is a neoplasm of thymic fat (2). There is no sex or age predilection and affected patients range in age from 3-76 years. Most patients remain asymptomatic until the size of the lesion produced local mass effects, resulting in symptoms such as cough, dyspnea, hemoptysis, chest pain and hoarseness (1,3). Autoimmune diseases, including myasthenia gravis, systemic lupus erythematosus, hypogammaglobulinemia, Graves’ disease, and erythroblastopenia, may coexist in 10% patients (1).

When thymolipomas are small, the lesion may not be detectable at chest radiography. When the lesion grows larger, it classically usually “drapes” around the heart and may simulate cardiomegaly (4). Extremely large thymolipomas have been described and can mimic pericardial effusion, pericardial cysts or pericardial tumors (5). Ultrasound can be used to differentiate fluid-containing lesions, such as pericardial effusion and cysts, from the echogenic fat typical of thymolipoma (4). Excessive epicardial fat, diaphragmatic elevation, sequestration or lobar collapse may also mimic this condition at chest radiography, whereas CT and/or MRI are diagnostic, revealing circumscribed anterior mediastinal fatty mass containing islands and strands of soft tissues with no invasion of adjacent structures (3-5).

Important differential diagnostic considerations for thymolipoma at cross sectional imaging include other fat-containing mediastinal masses such as mediastinal lipoma, mediastinal lipomatosis, liposarcoma and lipoblastoma. Lipomas are encapsulated whereas liopmatosis is an unencapsulated deposition of adipose tissues, and both lesions typically show homogeneous fat attenuation with no soft tissue strands. Liposarcoma frequently occurs in the posterior mediastinum and is usually symptomatic at the time of presentation, and often manifests with inhomogeneous appearance and invasion of subjacent mediastinal structures on CT/ or MRI (6). Lipoblastoma usually occurs under the age of 3, and shows intratumoral soft tissue stranding. Thymomas do not contain fatty tissue whereas some germ cell neoplasms contain cystic areas and calcification in addition to the fatty tissue (3,6). CT is considered the modality of choice for the evaluation of mediastinal masses in general, and thymolipoma in particular. For patients in whom CT findings are equivocal, or for patients with contraindications to enhanced CT (such as contrast media allergy) MRI may be utilized for further characterization of mediastinal lesions, such as thymolipoma. Encasement or invasion of the mediastinal vasculature, esophagus, and trachea as well as involvement of the pericardium, myocardium, and pleura are accurately detected with MRI. The primary disadvantages of using MRI for mediastinal lesion characterization include limited identification of calcifications, longer imaging time, and higher cost (3,6). Since thymolipomas are benign, and typically well encapsulated, with no invasion of surrounding structures, if detected incidentally, the lesion can be followed with imaging. However, when symptoms related to local mass effect develop, surgical resection is the treatment of choice which can be performed using a minimally invasive approach, such as thoracoscopic excision, with open resection reserved for larger lesions (7). Histopathological examination of thymolipoma reveals mature adipose tissue and hyperplastic thymic structures with Hassall’s corpuscles (2).

Amit Kumar Paliwal MD¹, Dr. Pradeep Jaiswal MCH (CTVS) AH

(R&R)², and Dr. Vivek Sharma MD³

¹Military Hospital Dehradun, Dehradun, Uttrakhand, India      

²Delhi Cantt, Delhi, India

³Command Hospital (CC), Lucknow, India

References

1. Dongel I, Imamoglu H, Şahin AF, Yıldırım S, Bayram M. A rare mediastinal tumor: thymolipoma. Eur J Gen Med. 2014;11:21-3. [CrossRef]
2. Hudacko R, Aviv H, Langenfeld J, Fyfe B. Thymolipoma: Clues to pathogenesis revealed by cytogenetics. Ann Diagn Pathol. 2009;13:185-8.[CrossRef] [PubMed]
3. Tomiyama N, Honda O, Tsubamoto M et al. Anterior mediastinal tumors: diagnostic accuracy of CT and MRI. Eur J Radiol. 2009;69(2):280-8. [CrossRef] [PubMed]
4. Yeh HC, Gordon A, Kirschner PA, Cohen BA. Computed tomography and sonography of thymolipoma. AJR Am J Roentgenol. 1983;140(6):1131-3. [CrossRef] [PubMed]
5. Gamanagatti S, Sharma R, Hatimota P, Guleria R, Arvind S. Giant thymolipoma. AJR Am J Roentgenol. 2005;185(1):283-4. [CrossRef] [PubMed]
6. Juanpere S, Canete N, Ortuno P, Martínez S, Sanchez, G, Bernado L. A diagnostic approach to the mediastinal masses. Insights Imaging. 2013;4(1):29-52. [CrossRef] [PubMed]
7. Carapinha CP, Wainwright L, Loveland JA. A giant thymolipoma. S Afr J Child Health. 2010;4(1):20-1.

Cite as: Paliwal AK, Jaiswal P, Sharma V. Medical image of the month: thymolipoma. Southwest J Pulm Crit Care. 2019;18(6):152-4. doi: https://doi.org/10.13175/swjpcc018-19 PDF

Medical Image of the Week: Fast-growing Primary Malignant Mediastinal Mixed Germ Cell Tumor

Figure 1. A: Chest radiograph taken 3 months prior to presentation. B: Chest radiograph showing large mediastinal mass (arrows). C: Coronal view of thoracic CT in soft tissue windows showing the large mediastinal mass (arrows). D: Lateral view of thoracic CT showing large mediastinal mass.

A 28-year-old man presented with progressive hemoptysis for two weeks. He had fever, cough, and night sweats for one month prior to admission that was treated as inflenza, bronchitis and/or pneumonia. He had started to experience anorexia, dysphagia, fatigue, a 30-pound weight loss, panic attacks, and the new onset of hypertension during the 3 months prior to admission. He also had intermittent middle chest pain that was aggravated by coughing for 5 months, but a cardiac catherization two months prior failed to show an abnormality. The chest x-ray and CT scan on this admission demonstrated a 15 cm large anterior mediastinal mass exerting a mass effect on the heart and medistial lymphadenopathy (Figure 1-B,C,D) which were absent on a chest x-ray performed 3 months prior to admission (Figure 1A). Core biopsy and immunohistochemical staining revealed a mixed germ cell tumor with components of seminoma and yolk-sac tumor. He was started on chemotherapy, to which he responded well. The malignant mediastinal germ cell tumor in this case is fast-growing and most likely of extragonadal origin. The majority of tumors occ in men between 20 and 35 years (1). The symptoms of these tumor and nonspecific as described in our case, which may lead to a low index of suspicion of malignant tumor with resultant delayed diagnosis.

Yufei Tian, Stella Pak, and Qiang Nai

Department of Medicine

University of Toledo Medical Center

Toledo, Ohio USA

Reference

1. Carter BW, Marom EM, Detterbeck FC. Approaching the patient with an anterior mediastinal mass: a guide for clinicians. J Thorac Oncol. 2014 Sep;9(9 Suppl 2):S102-9. [CrossRef] [PubMed]

Cite as: Tian Y, Pak S, Nai Q. Medical image of the week: fast-growing primary malignant mediastinal mixed germ cell tumor. Southwest J Pulm Crit Care. 2017;15(3):114-5. doi: https://doi.org/10.13175/swjpcc103-17 PDF

Medical Image of the Week: Remote Calvarial Renal Cell Metastases

Figure 1. Contrast enhanced axial MRI image shows the metastatic lesion in the right skull with mass effect and midline shift.

Figure 2. Coronal Image shows the extensive calvarial metastatic lesion and its mass effect.

A 57-year-old woman with past medical history significant for clear cell renal carcinoma and radical nephrectomy 9 years prior was admitted to our hospital for headache and left hemiparesis with associated numbness. Symptoms were progressive and had begun about 5 days prior to her presenting to our emergency department. Neurologic exam was significant for reduced strength in her left upper and lower extremities as well as well as sensory deficit to fine touch and vibratory sensation in her left arm. Her gait was unsteady and she was unable to ambulate without assistance. Her right calvarium was grossly enlarged and asymmetrical with softening of the underlying boney structures. 

MRI of the brain showed a 10 cm x 5 cm mass that was obliterating the calvarium and invading the dura mater (Figure 1).  There was mass effect with shift of the midline structures from right to left by approximately 6.5 mm (Figures 1 and 2). This was biopsy proven to be metastatic renal cell carcinoma. Additional smaller calvarium lesions were also seen. At least 3 and possibly 4 parenchymal metastatic deposits are seen in the left occipital lobe. Renal cell carcinoma has been well described to recur after long periods of remission, up to 33 years (1).

She was initially treated with intravenous dexamethasone with resolution of symptoms after 48 hours. Palliative radiation is being provided at this time.

Anthony Witten MD, Hem Desai MD, Ryan Wong MD and Joao Ferreira MD

Department of Internal Medicine

University of Arizona College of Medicine

Tucson, AZ USA

Reference

1. Parada SA, Franklin JM, Uribe PS, Manoso MW. Renal cell carcinoma metastases to bone after a 33-year remission. Orthopedics. 2009 Jun;32(6):446. [CrossRef] [PubMed]

Cite as: Witten A, Desai H, Wong R, Ferreira J. Medical image of the week: calvairial renal cell metastases. Southwest J Pulm Crit Care. 2016;12(1):32-3. doi: http://dx.doi.org/10.13175/swjpcc154-15 PDF

Medical Image of the Week: Pneumocephalus

Figure 1. Coronal CT Scan Image (Brain Lab Protocol) showing air in continuity with the frontal sinuses where there is no bone between the frontal sinus and the brain.

A 53-year-old woman underwent left craniotomy at an outside hospital after a trauma related to a motor vehicle accident. She was recovering well from her surgery. Two months later she started having headache and noticed progressive difficulty with word finding. She also reported periodic rhinorrhea upon further questioning. She presented to the emergency room at an outside hospital where a CT head was done. She was subsequently transferred to our ICU for higher level of care. Her CT Head revealed pneumocephalus involving the left frontal lobe along with regional mass effect leading to left to right shift of the anterior interhemispheric fissure. A dedicated brain lab protocol showed air in continuity with the frontal sinuses with a bone defect between the frontal sinus and the brain. She was evaluated by ENT and Neurosurgery services. She was placed on 100% oxygen via non-rebreather mask, frequent neuro-checks and a redo of the left frontal craniotomy for repair of the skull base defect was performed.

Administration of postsurgical supplemental oxygen through a non-rebreather mask has shown to significantly increase the absorption rate of postcraniotomy pneumocephalus as compared with breathing room air (1). In a prospective study of thirteen patients with postoperative pneumocephalus that was estimated to be > 30 ml were alternately assigned to breathe 100% oxygen using a nonrebreather mask (treatment group) or to breathe room air (control group) for 24 hours. There was a significant difference (p = 0.009) between the mean rate of pneumocephalus volume reduction in the treatment (65%) and control groups (31%) per 24 hours.

Tauseef Afaq Siddiqi MD, Enas M. Al Zaghal MD, and Sairam Parthasarathy MD

Division of Pulmonary, Allergy, Critical Care and Sleep Medicine

The University of Arizona

Tucson, AZ

Reference

1. Gore PA, Maan H, Chang S, Pitt AM, Spetzler RF, Nakaji P. Normobaric oxygen therapy strategies in the treatment of postcraniotomy pneumocephalus. J Neurosurg. 2008;108(5):926-9. [CrossRef] [PubMed] 

Reference as: Siddiqi TA, Zaghal EM, Parthasarathy S. Medical image of the week: pneumocepahlus. Southwest J Pulm Crit Care. 2014;9(1):57-8. doi: http://dx.doi.org/10.13175/swjpcc095-14 PDF