myelolipoma

骨髄脂肪腫

• (病名)骨髄脂肪腫

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出典(authority):フリー百科事典『ウィキペディア（Wikipedia）』「2016/11/01 15:32:17」(JST)

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Myelolipoma
An adrenal myelolipoma
Classification and external resources
Specialty	oncology
ICD-10	D17
ICD-O	M8870/0
eMedicine	radiology/genitourinary/376700
MeSH	D018209

Myelolipoma (myelo-, from the ancient greek μυελός, marrow; lipo, meaning of, or pertaining to, fat; -oma, meaning tumor or mass) is a benign tumor-like lesion composed of mature adipose (fat) tissue and haematopoietic (blood-forming) elements in various proportions.

Myelolipomas can present in the adrenal gland, or outside of the gland.

Causes

Although several hypotheses have been proposed as to the cause of myelolipoma, the causative process is still not clearly understood. Recent experimental evidence suggests that both the myeloid and lipomatous elements have a monoclonal origin, which strongly supports the hypothesis that myelolipomas are neoplastic lesions.

Older theories proposing a non-neoplastic origin include the following:

• Adrenal cortical cells, or other cells within the stroma of the adrenal cortex that are able to differentiate, may reversibly change into fat or blood-forming cells. This might occur because of the actions of adrenal cortex hormones, or of hormones released by the pituitary gland that act on the adrenal glands, such as adrenocorticotropic hormone (ACTH).
• The blood-forming cells may arise by differentiation of cells within the capillaries of the adrenal gland.
• Myelolipoma simply represents a site of normal blood formation outside the bone marrow.

Epidemiology

Myelolipomas are rare. They have been reported to be found unexpectedly at autopsy in 0.08% to 0.4% of cases (i.e.: somewhere between 8 per 10,000 and 4 per 1,000 autopsies). They most commonly occur in the adrenal gland, yet only comprise about 3% of all adrenal tumours. They may also occur in other sites, such as the mediastinum, the liver and the gastrointestinal tract.

There is no gender predilection, males and females are affected equally. The peak age range at diagnosis is between 40 and 79 years of age.

Symptoms and signs

The majority of myelolipomas are asymptomatic. Most do not produce any adrenal hormones. Most are only discovered as a result of investigation for another problem.

When myelolipomas do produce symptoms, it is usually because they have become large, and are pressing on other organs or tissues nearby. Symptoms include pain in the abdomen or flank, blood in the urine, a palpable lump or high blood pressure.

As they are benign tumors, myelolipomas do not spread to other body parts. Larger myelolipomas are at risk of localised tissue death and bleeding, which may cause a retroperitoneal haemorrhage.

Medical investigation

Myeloplipoma shown on a CT scan image

?Myelolipoma in Ultrasound

Most myelolipomas are unexpected findings on CT scans and MRI scans of the abdomen. They may sometimes be seen on a plain X-ray films.

Fine needle aspiration may be performed to obtain cells for microscopic diagnosis.

Treatment

Small myelolipomas generally do not produce symptoms, and do not require treatment. Ongoing surveillance of these lesions by a doctor is recommended. Surgical excision (removal) is recommended for large myelolipomas because of the risk of bleeding complications.

Pathology

Macroscopic features

Myelolipomas are usually found to occur alone in one adrenal gland, but not both. They can vary widely in size, from as small as a few millimetres to as large as 34 centimeters in diameter. The cut surface has colours varying from yellow to red to mahogany brown, depending on the distribution of fat, blood, and blood-forming cells. The cut surface of larger myelolipomas may contain haemorrhage or infarction.

• A macroscopic photograph of an adrenal myelolipoma. A remnant of the adrenal gland can be seen at the top

• The cut surface shows colour variegation from yellow to red to brown depending on the distribution of fat, blood and myeloid elements

Microscopic features

The microscopic view of a myelolipoma shows the presence of normal adrenal cells, fat (adipose) cells, and the three lineages of the myeloid precursors

The typical microscopic features of myelolipomas are shown in the image. There is a mixture of normal adrenal tissue, fat, and a full trilineage maturation of the three major blood-forming elements: myeloid (white blood cell forming), erythroid (red blood cell forming), and megakaryocytic (platelet forming) lines.

References

UpToDate Contents

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• 1. 副腎偶発腫 the adrenal incidentaloma

English Journal

• Adrenal incidentaloma does it require surgical treatment? Case report and review of literature.

• Yalagachin GH, Bhat BK.SourceDepartment of Surgery, Karnataka Institute of Medical Sciences, Vidyanagar, Hubli 580022, Karnataka, India. Electronic address: d.yalagachin@yahoo.com.
• International journal of surgery case reports.Int J Surg Case Rep.2013;4(2):192-4. doi: 10.1016/j.ijscr.2012.09.014. Epub 2012 Nov 16.
• INTRODUCTION: Adrenal incidentalomas have a prevalence of at least 5% in the general population. Among these adrenal myelolipoma are rare nonfunctioning tumors of adrenal with an incidence of 0.1-0.2% as documented in CT and autopsy series. We report such a rare case of adrenal myelolipoma incidenta
• PMID 23276765

• Imaging of traumatic adrenal injury.

• To'o KJ, Duddalwar VA.SourceDepartment of Radiology, Keck School of Medicine of University of Southern California, 1441 Eastlake Avenue, Rm G360C, Los Angeles, CA 90033-0377, USA. Katherine.Too@med.usc.edu
• Emergency radiology.Emerg Radiol.2012 Dec;19(6):499-503. doi: 10.1007/s10140-012-1063-y. Epub 2012 Aug 16.
• Traumatic adrenal injury is a relatively rare event, reported in 0.15 to 4 % of blunt abdominal trauma cases. The location of the adrenal glands, protected deeply within the retroperitoneum, accounts for the rarity of adrenal trauma. These injuries are unilateral in 75 to 90 % of cases and most comm
• PMID 22895661

• Bilateral adrenal lesions.

• Gupta P, Bhalla A, Sharma R.SourceDepartment of Radiodiagnosis, All India Institute of Medical Sciences, New Delhi, India.
• Journal of medical imaging and radiation oncology.J Med Imaging Radiat Oncol.2012 Dec;56(6):636-45. doi: 10.1111/j.1754-9485.2012.02435.x. Epub 2012 Sep 27.
• Bilateral adrenal lesions include a spectrum of disorders: neoplastic disorders (metastases, lymphoma, bilateral phaeochromocytoma, adrenocortical carcinoma and myelolipoma); longstanding congenital adrenal hyperplasia and macronodular adrenal hyperplasia; infections such as tuberculosis, histoplasm
• PMID 23210583

Japanese Journal

• 腎門部 extra-adrenal myelolipoma の1例

• 林 昭伸,宮里 朝矩,松崎 晶子,小菅 則豪,青山 肇,齊尾 征直,吉見 直己
• 診断病理 : Japanese journal of diagnostic pathology 28(3), 195-197, 2011-07-30
• NAID 10029598406

• 原発性肺癌に併発した多発性後縦隔骨髄脂肪腫の1例

• 藤原 隆行,朝戸 裕二,清嶋 護之,佐藤 始広,飯嶋 達生,雨宮 隆太
• 肺癌 51(3), 207-211, 2011
• 背景．骨髄脂肪腫は骨髄成分と成熟脂肪組織からなる稀な良性腫瘍である．副腎原発が多く，後縦隔原発例は稀である．症例．既往に多血症，高血圧症，糖尿病を有する71歳男性である．食欲不振を主訴に近医受診し，胸部X線および胸部CTにおいて肺および縦隔の異常陰影を指摘され，当院を紹介受診した．胸部CTにおいて，右肺S1に15 mm大の結節影，両側後縦隔の第3胸椎に接し腫瘤性病変を認めた．FDG-PETでは右肺 …
• NAID 130000761275

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• 骨髄脂肪腫の画像診断(myelolipoma、副腎)

Sponsored Link 目次1 骨髄脂肪腫1.1 画像所見1.1.1 症例① 60歳代女性1.1.2 症例② 20歳代女性1.1.3 症例③ 70歳代男性 myelolipoma疑い。2 関連記事はこちら 骨髄脂肪

• myelolipoma

副腎myelolipoma 自験例l例と外科的切除例79例に関する文献的考察 (449) はじめに 副腎のmyelolipomaは，きわめて稀に見られる良性 腫療であり，従前の報告例はほとんどが剖検時に発見さ れたものである.近年，超音波検査・CT検査 ...

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