1 Background

Angiomyolipomas are rare mesenchymal tumours arising from the perivascular epithelioid cells. They are benign endocrinologically inactive tumours with a histological structure consisting of variable amounts of adipose, thick-walled blood vessels and smooth muscle cells [1]. Commonly, angiomyolipomas occur in the kidney with few extra renal case reports in adrenals, bone, breast, colon, heart, liver, lung, parotid gland, retroperitoneum, skin and spermatic cord [2,3,4,5].

2 Case presentation

A 45-year-old lady, previously fit and well, presented with a 3-week history of right loin pain, nausea and vomiting. At presentation, her vital signs and abdominal examination were normal. A full blood count and urea and electrolytes were at baseline; C-reactive protein was elevated at 103 mg/L.

CT scan showed a right adrenal angiomyolipoma measuring 6.3 × 6.8 cm with intralesional haemorrhage (Fig. 1). Due to the large size, haemorrhage and symptoms, the patient underwent an open right adrenalectomy. She was discharged home just over 2 weeks post-operatively.

Fig. 1
figure 1

CT on initial presentation shows haemorrhage of the right adrenal angiomyolipoma (arrowed)

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Histology showed a soft tissue tumour composed of mature adipose tissue, proliferating thick-walled vessels and in a smaller quantity proliferation of smooth muscle, with focal spindle and epithelioid cells (Figs. 2, 3). Immunostains for Melan-A (Fig. 4) and HMB-45 were focally positive. Desmin and smooth muscle actin were also focally positive, confirming the presence of smooth muscle in the tumour. EVG stain showed the blood vessels, with loss of elastic lamina, which is in keeping with vessels in angiomyolipoma (Fig. 5). These histological features are consistent with an adrenal angiomyolipoma [1].

Fig. 2
figure 2

Adrenal gland with tumour. Haematoxylin and eosin staining (× 4)

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Fig. 3
figure 3

Tumour with epithelioid cells, fat and blood vessels. Haematoxylin and eosin staining (× 20)

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Fig. 4
figure 4

Melan-A positive spindle and epithelioid cells (× 20)

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Fig. 5
figure 5

Van Gieson’s EVG stain with loss of elastic lamina in blood vessels (× 4)

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The patient was reviewed in clinic 4 months post-operatively when she was asymptomatic, and a repeat CT scan showed no evidence of recurrence. At 36-month follow-up, she remained well.

3 Discussion

This case report describes spontaneous haemorrhage of an adrenal angiomyolipoma causing loin pain. Adrenal angiomyolipomas can also be picked up incidentally on imaging. The tumours are easily detectable from the pathognomonic feature of high-fat content. A review of the literature revealed 17 previously reported cases of adrenal angiomyolipoma. Of these, 14 were sporadic and 3 were reported in patients with tuberous sclerosis or lymphangioleiomyomatosis [2,3,4,5,6,7,8,9,10,11,12,13,14,15,16,17]. There was 1 reported case of spontaneous haemorrhage [4].

Angiomyolipomas can be difficult to differentiate histologically from sarcoma or sarcomatoid carcinoma. Immunostaining can be used to help confirm the diagnosis. Markers that have shown a high specificity and sensitivity for angiomyolipomas include: HMB-45, Melan-A, SMA (smooth muscle actin) and microphthalmia transcription factor. S-100 is also often used in diagnosis although not all studies have found a high sensitivity for its use [1].

Management of these lesions has been guided by the limited number of case reports in the literature. It is general consensus that smaller lesions detected incidentally should be managed non-surgically and their size should be kept under surveillance. Surgical management has been proposed for lesions which are either symptomatic and/or greater than 5 cm. Laparoscopic adrenalectomy has successfully been used, but larger lesions are best removed using open adrenalectomy [13]. Adrenal angiomyolipomas have the potential to become very large with the largest reported case being 15 × 16 cm [5]. There have been no reports of malignant change in these lesions; nevertheless, long follow-up is recommended because of the unknown clinical progression of these tumours [1].

4 Conclusion

Adrenal angiomyolipomas are rare benign tumours that have the ability to reach a large size and potential to bleed. Here, we report the second case of spontaneous haemorrhage in an adrenal angiomyolipoma, which was successfully treated with open adrenalectomy.