Ann Thorac Surg 2009;88:e39-e41. doi:10.1016/j.athoracsur.2009.06.085
© 2009 The Society of Thoracic Surgeons
Case Reports
Primary Myelolipoma of the Chest Wall
Dariusz Sagan, MD, PhDa,*,
Ma
gorzata Zdunek, MD, PhDb,
El
bieta Korobowicz, MD, PhDb
a Department of Thoracic Surgery, Medical University of Lublin, Lublin, Poland
b Department of Clinical Pathomorphology, Medical University of Lublin, Lublin, Poland
Accepted for publication June 18, 2009.
* Address correspondence to Dr Sagan, Department of Thoracic Surgery, Medical University of Lublin, Jaczewskiego 8, Lublin, 20-090, Poland (Email: dariusz.sagan{at}am.lublin.pl).
 |
Abstract
|
|---|
Myelolipoma is a rare neoplasm composed of an admixture of mature adipose tissue and hematopoietic elements. It typically occurs in adrenal glands as a solitary, well-circumscribed mass, and the thoracic location is extremely unusual. We present a 63-year-old man with an accidentally detected tumor of the chest wall. Thoracoscopic resection and subsequent histopathologic examination of the lesion revealed myelolipoma with bony spicules, which are an unusual component in this neoplasm. We discuss the etiology, histopathology, differential diagnosis, and recommended management of extra-adrenal myelolipoma, and we conclude that it should be considered in the differential diagnosis of subpleural chest wall tumors.
|
Introduction
|
|---|
Myelolipoma (ML) is a rare, benign neoplasm that is typically encountered in adult persons, usually with an asymptomatic course. It was first described by Gierke in 1905 and named by Oberling in 1929. Histologically, ML is composed of mature adipose tissue admixed with normal hematopoietic elements in varying proportions [1–6]. This tumor is most often found as a solitary lesion in adrenal glands; however, extra-adrenal myelolipoma (EAML) has occasionally been described in the retroperitoneum, mesentery, stomach, spleen, and liver. Thoracic location is very rare and only a few cases have been reported in the mediastinum and lungs [1–5]. We present a case of a primary myelolipoma located in the chest wall. We believe that this unique location of ML has not been previously described in the literature. The etiology, pathology, differential diagnosis, recommended management of EAML, and review of the literature are also presented.
A 63-year-old Caucasian man presented with a round shadow disclosed on a routine posteroanterior chest roentgenogram. A computed tomographic scan revealed a smooth, well-defined lesion (15 x 18 mm) located posterolaterally in the thoracic wall in the fourth right intercostal space (Fig 1). Except for this lesion, the patient was asymptomatic and all laboratory tests were normal. Because of indeterminate histology of the lesion, surgical removal was recommended. The patient was operated on with use of a minimally invasive thoracoscopic technique. An oval-shaped, brown-yellowish, well-circumscribed tumor was found on the interior surface of the thoracic wall under the parietal pleura. The lesion was dissected from the underlying intercostal muscles, and was completely removed. The patient had an uneventful postoperative course, and has remained relapse-free at the 82-month follow-up.
View larger version (90K):
[in this window]
[in a new window]
|
Fig 1. Computed tomographic scan reveals a smooth, well-defined, subpleural lesion (indicated by white arrows) (A) located in the intercostal space of the chest wall (B).
|
|
On pathologic examination the resected lesion measured 20 x 15 x 12 mm, was covered with a thin capsule, and a cut surface revealed yellow-brown tissue with foci of enhanced density. Microscopic examination disclosed scattered foci of hematopoietic tissue, including myeloid, erythroid, and megakaryocytic elements surrounded by clearly visible, thin bony spicules among adipose tissue (Fig 2). Based on these findings, extra-adrenal myelolipoma was diagnosed.
View larger version (48K):
[in this window]
[in a new window]
|
Fig 2. (A) Microscopic picture shows hematopoietic elements admixed with adipocytes (on the left) separated by a bony spicule (indicated by the black arrow). (Hematoxylin and eosin, x100). (B) High-power magnification (B) x400 and (C) x600 reveal normal hematopoietic cells, including erythropoietic, granulopoietic, and megakaryocytic cell lineages, as well as some adipocytes.
|
|
|
Comment
|
|---|
Myelolipoma is an uncommon benign neoplasm usually presenting as a small, solitary, encapsulated lesion located in the adrenal gland, although giant tumors have also been described [6]. Extra-adrenal ML is much more seldom and may occur in the liver, stomach, mesentery, spleen, retroperitoneum, pre-sacral area, or thorax [1, 2]. Thoracic location is very rare and only a few cases have been described [1–5]. In the majority of cases, ML is asymptomatic and usually found accidentally on roentgenogram, ultrasound examination, or autopsy. Giant ML may affect adjacent organs by compression and cause appropriate signs and symptoms including pain or even hemorrhage [7].
The hypotheses of the cause of ML include degenerative changes in hyperplastic tumor cells or adenomas of adrenal glands, metaplasia in primary stem mesenchymal cells of the adrenal cortex, and displacement of differentiated bone marrow cells during embriogenesis [8]. Other authors suggest metaplasia of reticulo-endothelial cells caused by prolonged stress, or development of ML from blood bone embolic material [6]. Many consider ML as a choristoma [4]. Chen and colleagues suggested that in patients with anemia, long-lasting erythropoietic stimulation may play a role in the development of ML [9]. Chromosomal translocations (3;21) (q25;p11), detected in ML cells by Chang and colleagues [10], are the same karyotype disorders that were observed in benign lipomatous neoplasms in patients with acute myelogenous leukemia or myelodysplastic syndromes. This suggests bone marrow origin of this tumor and may indicate that ML is derived from erroneously transferred erythroid cells. Occasionally ML may be accompanied by endocrine disorders like Cushing's syndrome, Addison's disease, Cohn's syndrome, phaeochromocytoma, adrenal gland cancer or adenoma, diabetes mellitus, or even obesity and hypertension [2, 8]. Therefore, some authors emphasize that development of ML may be correlated with prolonged excessive steroid production, or genome defects of the endocrine glands responsible for multiple endocrine neoplasia type 1 [9].
Scarce reports on thoracic EAML include mediastinal [1–4] and pulmonary location [5]. Our patient had EAML located subpleurally in the fourth right intercostal space on the interior surface of the posterolateral part of the chest wall (Fig 1B). This unique location of EAML has not been previously described in the literature.
In the presented case, gross examination results were typical for ML. However, on microscopic examination, among mature adipose tissue admixed with hematopoietic elements, we revealed bony spicules (Fig 2A), which are an unusual component in ML [5]. Some authors consider the bony spicules to be the result of osseous metaplasia, whereas others deny their presence in ML [2]. The case presented provided evidence that bony spicules may occur in ML, and we believe that they develop in the process of osseous metaplasia.
Differential diagnosis of subpleural chest wall masses should include lesions of similar clinical appearance, such as lipomas, lymph node metastases, neurogenic neoplasms, and in particular, extramedullary hematopoietic tumors. Although microscopically alike, in contrast to ML, extramedullary hematopoietic tumors typically present as multiple lesions involving various parenchymal organs and soft tissues. These lesions are accompanied by hepatosplenomegaly, and occur as a complication of chronic anemia in the course of hematologic diseases, including thalassemia, hereditary spherocytosis, or acute myelogenous leukemia [2, 8].
There is no agreement on optimal management of thoracic EAML. The majority of these tumors are surgically resected, considering the potentially progressive enlargement of the lesion and indeterminate preoperative diagnosis [1, 2]. Conservative resection is appropriate, because neither recurrence nor malignant transformation has been reported. In many cases a regular radiologic follow-up may be considered an alternative to avoid surgery, especially in patients with major contraindications for a surgical intervention. However, this management should be preceded by computed tomographic-guided fine needle biopsy to verify the tumor histology [5].
We present this case because of the unique location of myelolipoma in the intercostal space of the chest wall, which we believe has not been previously described in the literature. Although myelolipoma is rare, we suggest that it should be considered in the differential diagnoses of subpleural chest wall tumors.
|
References
|
|---|
- Vaziri M, Sadeghipour A, Pazooki A, Shoolami LZ. Primary mediastinal myelolipoma Ann Thorac Surg 2008;85:1805-1806.[Abstract/Free Full Text]
- Franiel T, Fleischer B, Raab BW, Fuzesi L. Bilateral thoracic extraadrenal myelolipoma Eur J Cardiothorac Surg 2004;26:1220-1222.[Abstract/Free Full Text]
- Minamiya Y, Abo S, Kitamura M, Izumi K. Mediastinal extraadreanal myelolipoma: report of a case Surg Today 1997;27:971-972.[Medline]
- Strimlan CV, Khasnabis S. Primary mediastinal myelolipoma Cleve Clin J Med 1993;60:69-71.[Medline]
- Sabate J, Shahian DM. Pulmonary myelolipoma Ann Thorac Surg 2002;74:573-575.[Abstract/Free Full Text]
- Wilhelmus JL, Schrodt GR, Alberhasky MT, Alcorn MO. Giant adrenal myelolipoma: case report and review of the literature Arch Pathol Lab Med 1981;105:532-535.[Medline]
- Lawler LP, Pickhardt PJ. Giant adrenal myelolipoma presenting with spontaneous hemorrhage. CT, MR and pathology correlation. Ir Med J 2001;94:231-233.[Medline]
- Dieckmann KP, Hamm B, Pickartz H, et al. Adrenal myelolipoma: clinical, radiologic and histologic features Urology 1987;29:1-8.[Medline]
- Chen KT, Felix EL, Flam MS. Extraadrenal myelolipoma Am J Clin Pathol 1982;78:386-389.[Medline]
- Chang KC, Chen PI, Huang ZH, Lin YM, Kuo PL. Adrenal myelolipoma with translocation (3;21)(q25;p11) Cancer Genet Cytogenet 2002;134:77-80.[Medline]
This article has been cited by other articles:
|
|
|
|
 
X. Li, S. Wickersham, P. Elgert, R. Zamuco, and Y. Shi
Multifocal Intra-abdominal Extra-adrenal Myelolipoma Diagnosed by Fine Needle Aspiration: A Case Report and Literature Review
Lab Med,
February 1, 2012;
43(2):
1 - 3.
[Abstract]
[Full Text]
[PDF]
|
|
|
Top
Abstract
Introduction
