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| Journal of the New Zealand Medical Association,
21-January-2011, Vol 124 No 1328
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Kheman Rajkomar, Isaac Cranshaw
Adrenal myelolipomas are benign and hormonally inactive
tumours that have been described in 1929 by the French pathologist, Professor
Charles Oberling.1 Microscopically it is made
up of adipose and hematopoietic tissue. Its pathogenesis is unclear but the
favoured mechanism is reticuloendotherlial call metaplasia that is triggered by
necrosis, infection or stress.2
This lesion is still not clearly defined as it is a rare
entity. The incidence is 0.08–0.2% as quoted by autopsy
series.3 Our knowledge is mainly based on
published case series and case reports.
The case reported here is the sixth largest such lesion
reported in the literature. Moreover it has some malignant radiological features
that distinguish it from other such reported lesions.
Case reportA 47-year-old man with schizophrenia presented to the
hospital in July 2008 with a urinary tract infection. On examination he had
abdominal distension and right flank tenderness. An abdominal ultrasound
revealed a large homogeneous mass, about 3700cc in volume, displacing the right
kidney inferomedially (Figure 1).
Figure 1. Ultrasound of right
flank
 The sonographic finding prompted a CT of the abdomen to
further define the lesion. A 22×22×16cm right retroperitoneal well
circumscribed mass was seen with mixed fat and soft tissue density. The right
lobe of the liver was indented, suggestive of invasion. A lesion was noted in
segment 8, which raised the possibility of metastatic liposarcoma (Figure 2).
Figure 2. CT abdomen – coronal view
showing the invasive lesion with a liver nodule
 Interestingly there was no paraortic lymphadenopathy noted
on radiological investigation.
On 23 July 2008, a trial of excision of this lesion was
attempted. A J-shaped incision was made on his right upper quadrant. A large
retroperitoneal mass was seen, with clear planes around the kidney, liver and
IVC. The adrenal gland was resected together with the mass. The liver lesions
noted on CT were haemangiomas. The specimen was 220×180×120mm, and
weighed 3695g (Figure 3).
Figure 3. Right retroperitoneal mass with
adrenal gland in the lower left corner
 The adrenal gland was distinct from the mass. On cut section
the lesion was fatty yellow with less than 20% patchy necrosis seen. The tumour
was made up of mature adipocytes and haematopoietic cells. No malignant tissue
was seen. The features were consistent with an adrenal myelolipoma.
Apart from an episode of opiate overdose the patient made an
uneventful recovery and was discharged from hospital eight days after admission.
DiscussionA PubMed search reveals that our case is the sixth largest
adrenal myelolipoma that has been reported (Table 1). Boudreaux et
al4 reported the second biggest one (5900g),
although it included the kidney and some retroperitoneal tissue too.
Table 1. Largest cases reported in
literature
Apart from its size, its radiological appearance was
singular. Adrenal lesions greater than 6cm with an inhomogeneous consistency are
more likely to be malignant.9 This
lesion’s bosselated appearance with mixed soft and fat tissue density on
CT was unusual for an adrenal myelipoma.
Those lesions are typically asymptomatic. However, they can
present with abdominal or flank pain as a result of haemorrhage, necrosis or
pressure effect on surrounding organs. A study of the largest series published
shows that they are mostly incidentally picked up on imaging. 58% and 75% of the
adrenal myelolipomas studied by Meyer et
al10and Han et
al11 respectively were asymptomatic.
Interestingly in Meyer’s series symptomatic myelolipomas were smaller than
ones picked up incidentally.
We also looked at the therapeutic options offered to
patients in both series. Meyer et al resected all the lesions from their
patients. Han et al on the other hand were selective, offering surgery to large
or symptomatic myelolipomas—i.e. to only 25% of their patients. Their
3-year clinical and radiological follow-up did not reveal any complications from
the adrenal myelolipomas.
We hope that as more cases get reported more light will be
shed on this rare lesion.
Author information: Kheman Rajkomar,
Surgical Registrar, General Surgery, Waikato Hospital, Hamilton; Isaac Cranshaw,
Endocrine Surgeon Auckland City Hospital, Auckland
Correspondence: Kheman Rajkomar, 51 Ohaupo
Road, Hamilton, New Zealand. Email: kheman205@yahoo.com
References:
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