An unusual site of extra-medullary haemopoietic tissue in a patient with a raised hemidiaphragm.

G. I. Varughese, U. Nandy, N. Iqbal, Y. L. Hock, A. J. Anwar.

Department of Endocrinology,
Manor Hospital , Walsall WS2 9PS, West Midlands, U.K.

Correspondence to:

Dr. G. I. Varughese MRCP ( Ireland ); MRCP ( U.K. )
Clinical Research Fellow
University Department of Medicine
ASCOT – Centre
City Hospital
Birmingham B18 7QH
Tel: 0121 507 5080
Fax: 0121 554 4083
Email: georgeiv@doctors.org.uk

INTRODUCTION

Adrenal incidentalomas are more commonly being found in clinical practice with the increasing use of various imaging techniques. The investigation and management of these patients remain controversial. We reviewed the literature and describe a patient who had bilateral adrenal masses diagnosed coincidentally and on biopsy found to have rather unusual bilateral benign myelolipomas.

CASE REPORT

A 70 year old man was admitted with a history of increasing shortness of breath for two weeks, which was gradually getting worse. He had undergone a triple vessel coronary artery bypass  graft surgery three weeks prior to the admission. He was also on treatment for hypertension and hyperlipidaemia with Bisoprolol and Simvastatin respectively. His other medications included Paracetamol and Aspirin. There was no other past medical history of  note.  He was found to be anaemic with a haemoglobin level of 9.8g/dl and this was thought to be post-operative. All the other blood tests were unremarkable except for hypoxia on arterial blood gas analysis. Systemic examination revealed decreased air entry bilaterally and he also had a scattered wheeze with few basal crepitations. Troponin-I level was less then 0.2μg/l (normal range). Echocardiogram showed no evidence of cardiac dysfunction. Ventilation-Perfusion scan of the lungs showed a very low probability for pulmonary emboli. Chest X-ray showed infective changes in both lung fields with a raised hemi-diaphragm on the right side. A sub-phrenic abscess was queried in view of these findings and an ultrasound scan showed a large mass arising from the right suprarenal region. Computed tomography (C.T.) scan of the chest and abdomen revealed a large 8cm right suprarenal mass and another 4cm left adrenal mass both of which were of predominantly fat intensity, and the appearances were in keeping with bilateral adrenal adenomas (Image 1).  24 hour urine catecholamines (Noradrenaline 292nmol/24 hours [normal range 76-561], Adrenaline 24nmol/24hours [normal range 7-82], and Dopamine was 1187nmol/24 hours [normal range 366-2897]. A short synacthen test was within normal limits with a basal cortisol of 155nmol/l rising to 731nmol/l and 891 nmol/l at 30 minutes and 60minutes respectively following the short synacthen test. CT guided biopsy of the adrenal glands were carried out and the histology showed adipose tissue containing haemopoietic tissue, which represented haemopoietic marrow. Histological features were essentially of extra-medullary haemopoiesis with some mature adipose tissue, consistent with benign myelolipoma of the adrenal gland (Image 2).

DISCUSSION

The increased use of radiological investigations like abdominal ultrasonography, computedtomography, and magnetic resonance imaging has led to the classification of adrenal lesions termed the incidentally identified adrenal mass or adrenal incidentaloma. Unlike for the large, clinically, or biochemically symptomatic adrenal mass, the evaluation of patients with small, asymptomatic, or nonfunctional adrenal lesions remains controversial [1]. The evaluation of these adrenal incidentalomas presents a difficult challenge to both endocrinologists and radiologists and they felt that a multidisciplinary approach with biochemical screening and radiologic evaluation is essential to assess the nature and function of these lesions. Furthermore, the importance of identifying patients who are morbidly affected by hormonal hypersecretion or malignant potential cannot be emphasised more.  Reports have shown the importance of investigating these patients for hypersecretory adrenal tumours, as 98 out of the 126 patients they had followed up had to undergo operations [2]. All the patients who had non-secretory adenomas had a size less than 6cm, and in those who had adrenal carcinomas were above 6cm. In the patient we have described the adenoma on the right side was 8cm in size. Non-functioning cortical adenomas less than 4 to 5 cm in size should be followed clinically and radiographically [3]. Laparoscopic adrenalectomy has been used increasingly as the preferred approach in patients who require surgical resection whereas open adrenalectomy is reserved for patients with large, malignant tumors. They also emphasised that the indications for adrenalectomy in patients with nonfunctioning adrenal tumours should not be liberalized because of the laparoscopic approach. Other reports showed that patients with an adrenal incidentaloma are at risk for tumor growth and development of hormonal alterations [4]. The risk of adrenal malignancy, although not elevated, also indicates the need for long-term follow-up.

Myelolipomas of the adrenal gland were first described in 1905. They are rare cortical, nonfunctioning, benign neoplasms, generally unilateral, usually discovered by accident or at autopsy.  These tumours are made up of fat and hematopoietic cells. Their origin is unclear and different theories have been put forward, including development from rests of mesenchymal stem cells, embolism of bone marrow, extramedullary hematopoiesis and, according to the most widely accepted theory, metaplasia of the reticuloendothelial cells of blood capillaries. A non invasive method of diagnosing adrenal extra-medullary haemopoiesis by bone marrow scintigraphy using Technetium Tc-99m has been demonstrated [5]. Patients may present without subjective symptoms and still require surgical excision [6]. Radiologic recognition and fine-needle biopsy of these lesions are important to avoid unnecessary surgery in asymptomatic cases [7]. There has also been suggestions that since the lesions cannot be regarded as true neoplasms, the name myelolipoma should be replaced by the term myelolipomatous nodule [7].

The increasing number of incidentally discovered adrenal myelolipomas raises the question of appropriate treatment modalities, which range from watchful waiting to surgical removal. The incidence of adrenal myelolipomas at autopsy is low (0.2%) and due to their uncertain etiology and low frequency, management of adrenal myelolipomas is usually individualized [8].

Though a majority of these tumours are not hormonally active, recent evidence suggests that hormonal secretion, particularly in the form of subtle hypercortisolism is common [9].

However clinical judgement based on the patient’s history, age and general condition should remain the most significant determinant in the final decision making, and an adrenal lesion which is more than 4cm in size should be evaluated further. [10].

Keywords: Adrenal glands, Adenoma, Myelolipoma

Acknowledgements:

Dr. H. Rai, Consultant Radiologist, Manor Hospital , Walsall .  

Image 2 (Histology of adrenal gland biopsy)

SUMMARY POINTS

· Adrenal incidentalomas (adrenal masses in patients with no gross evidence of adrenal disease) is becoming a common clinical problem with the increased availability of radiological investigations.
· The vast majority are benign, though some may undergo malignant transformation.
· Adrenal incidentalomas may become hormonally active.
· Adrenal glands are a common site for metastatic deposits, hence further clinical evaluation is needed.· Asymptomatic patients with large sized incidentalomas may require surgery.
· Long term follow up of these patients is advised.
· Clinical judgement in individual patients should remain important in decision making. 

REFERENCES

1. Munver R, Fromer DL, Watson RA, Sawczuk IS. Evaluation of the incidentally discovered adrenal mass. Curr Urol Rep 2004; 5(1): 73-7.
2. Li HZ, Yan WG, Wang W, Xia M, Wang HJ, Liu GH. Adrenal incidentalomas: report of 126 cases. Zhonghua Wai Ke Za Zhi 2004;42(2): 97-9.

3.  Brunt LM, Moley JF. Adrenal incidentaloma. World J Surg 2001;25(7): 905-13.

4.      Libe R, Dall'Asta C, Barbetta L, Baccarelli A, Beck-Peccoz P, Ambrosi B.  Long-term follow-up study of patients with adrenal incidentalomas. Eur J Endocrinol 2002;147(4): 489-94.

5.Wat NM , Tse KK, Chan FL , Lam KS . Adrenal extramedullary haemopoiesis: diagnosis by a non-invasive method. Br J Haematol 1998;100(4): 725-7.    

6.  Imamura R, Kinouchi T, Fujimoto M et al. Bilateral synchronous adrenal myelolipomas: a case report. Hinyokika Kiyo 1998;44(11): 801-3.    

7. Bautista DV, Asch M, Kovacs K et al Murray D. Adrenal myelolipomatous nodules mimicking adrenal neoplasms: report of three cases. Can J Surg 1989;32(1): 51-5.    
8. Segura Martin M; Lorenzo Romero JG; Salinas Sanchez AA et al. Bilateral adrenal myelolipoma. Urol Int 1999;(4):226-8.    
9. Aron DC . Adrenal incidentalomas and glucocorticoid autonomy. Clinical Endocrinology 1998;49:157-8.
10. Tsagarakis S. Investigation and Management of  adrenal incidentalomas. CME Bulletin Endocrinology & Diabetes 2000;3(2):41-5

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