Chinese Medical Journal 2008;121(16):1598-1600
Myxoid adrenocortical adenoma: a case report

ZHU Yu,  WU Yu-xuan,  ZHANG Chong-yu,  ZHAO Ju-ping,  RUI Wen-bin,  HE Hong-chao,  SHEN Zhou-jun

ZHU Yu (Department of Urology, Ruijin Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai 200025, China)

WU Yu-xuan (Department of Urology, Ruijin Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai 200025, China)

ZHANG Chong-yu (Department of Urology, Ruijin Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai 200025, China)

ZHAO Ju-ping (Department of Urology, Ruijin Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai 200025, China)

RUI Wen-bin (Department of Urology, Ruijin Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai 200025, China)

HE Hong-chao (Department of Urology, Ruijin Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai 200025, China)

SHEN Zhou-jun (Department of Urology, Ruijin Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai 200025, China)

Correspondence to:ZHU Yu,Department of Urology, Ruijin Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai 200025, China (Tel: 86-13611633147. Fax:. E-mail:zyyyhyq@ 126.com)
Keywords
Abstract

Myxoid adrenocortical adenomas are extremely rare with only 24 cases reported.1-12 The first case was reported by Tang et al1 in 1979 which was diagnosed as a myxoid adrenocortical carcinoma. Nearly all the reports were of single case except Brown et al3 who described a group of 14 cases. We report here an additional case of myxoid adrenocortical adenoma with an immuno- histochemical study of the tumor and discuss the diagnosis with reference to the current literature.

CASE REPORT

A 66-year-old man was admitted to the department of urology at Ruijin Hospital with a right adrenal mass discovered during a routine physical examination. The patient had been suffering from hypertension for 11 years. The blood pressure levels were 150–160/90–100 mmHg on Nimodipine treatment. No Cushing’s syndrome features were observed.

Laboratory examinations were all in the normal range with the exception of the basic value of plasma angiotensin (10 pg/ml, normal range: 18–103 pg/ml), which was slightly decreased. Ultrasonography demonstrated a solid mass in the right adrenal gland of 51 mm×49 mm×55 mm. Intravenous pyelography showed a hyperdense mass in the right adrenal area which made the right kidney lower than usual. A CT angiography scan indicated a well-circumscribed mass of approximately 50 mm in diameter (52 mm×50 mm) in the right adrenal gland which was smooth at the edge and clear in the boundary. The mass was so close to the inferior vena cava that the inferior vena cava was compressed (Figure 1). After contrast administration the CT scan indicated that the mass enhanced inhomogeneously. A 131I-MIBG scan was negative and no metastatic lesions were found in any region.


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Figure 1. CTA indicates a mass at the right adrenal area, and is slightly close the inferior vena cava. The inferior vena cava is compressed.

A nonfunctional right adrenal tumor was suspected, and a right adrenalectomy was performed under general anesthesia. The blood pressure and heart rhythm were stable during the operation. Grossly, the adrenal tumor with attached fibrofatty tissue were 60 mm×45 mm×40 mm and weighted 83 g. The cut surface was composed of grey-yellow faintly nodular areas that were surrounded by grey-brown gelatinous areas. By light microscopy the tumor cells have architectural patterns that are alveolar and are arranged in cords. A pseudoglandular pattern with myxoid luminal contents was noted in limited areas. The tumor cells contained abundant cytoplasm which was eosinophilic or vesicular. Pigment granules could be found partially intra-cytoplasmic. The tumor cell nuclei were small and round and mitosis was rare. There was focal aggregation of some adipose tissue and infiltration of lymphocytes at the edge of the tumor. Immunohistochemical staining revealed that the tumor cells were positive for melan-A (Figure 2A), inhibin-α (Figure 2B), synaptophysin (Figure 2C), vimentin (Figure 2D) and calretinin, but were negative for S-100 and AE1/AE3. Ki-67, the labeling index was below 1% because few cells were immunostained with the MIB-1 antibodies. Pathological findings confirmed the tumor as myxoid adrenocortical adenoma. Neither recurrence nor metastasis was detected during follow-up for the subsequence 12 months.


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Figure 2. Light microscopy indicates that melan-1(A), inhibin-α (B), synaptophysin (C) and vimentin (D) are positive in the cytoplasm of tumor cells (HE, original magnification×200).

DISCUSSION

Myxoid adrenocortical tumors are extremely rare, and can be classified into adenoma or carcinoma. The previous reported cases included 10 adenomas and 14 carcinomas, and the age of patients ranged from 16 to 73 years. Although Brown et al3 found a female predominance in both benign and malignant myxoid adrenocortical tumors, the over-all female-to-male ratio was 12/12 (5/5 for the adenomas and 7/7 for the carcinomas).1-12 The clinical manifestations are similar to the other types of adrenocortical tumors which are mostly nonfunctional tumors. Some patients may have hypertension with cortisol and aldosterone levels slightly elevated, while some patients may present with related endocrine symptoms.3 In our report the patient was a 66-year-old male with the history of hypertension for 11 years. Endocrine evaluations and imaging examinations indicated a nonfunctional adrenocortical tumor in the right adrenal gland.

Myxoid adrenocortical tumors are characterized by the presence of abundant extracellular myxoid material which is mostly acidic mucopolysaccharides. Myxoid areas range from as little as 10% of the tumor to more than 90% in some case.3 Although Forsthoefel proposed that the mechanism of production of myxoid material might be a degenerative process, or produced by tumor cells, the origin of myxoid material in the tumor has been unidentified until recently.2,4 In the report by Brown et al3 the average size of the myxoid area in the nonfunctional tumor was higher than that in the functional tumor. The myoxid area in our case approached 90%.

With the exception of variation in their myxoid composition, atrophic adrenocortical parenchyma was found in most of the cases. The tumor cells were polygonal in shape with abundant cytoplasm, which was hypochromatic and rich in lipids. The cells exhibited a number of architectural patterns such as a glandular tubular pattern, network pattern, sheet or cord pattern. The cells appeared to float in a myxoid background divided into small lobules by fibrovascular stroma, or formed bordered clusters.3,6 By electron microscopy, abundant mitochondria with rough and smooth endoplasmic reticulum were visible in the cytoplasm.4,9 The positive immunostaining of adrenocortical tumor markers such as melan-A, inhibin-α and synaptophysin play an important role in recognizing the tumor’s histological sources.7,9

By the pathological classification, myxoid adrenocortical tumors can mainly be divided into two types: adenoma and carcinoma. Grossly, most of the adenomas were single nodule, gray-yellow colored with a complete capsule, weighting less than 100 g and measuring 7.5 cm or less at their greatest diameter. The carcinomas were generally larger than the adenomas, most weighting more than 100 g and measuring 8 cm or more at their greatest diameter.3 Under a light microscope, cells were mildly to moderately pleomorphic and distinct nucleoli were observed in myxoid adrenocortical adenoma, and mitoses counted three or less per 10 high power fields (HPF). No necrosis or vascular invasion was observed in adenomas, while focal capsular invasion was seen in some cases. However, necrosis and vascular or capsular invasion were observed in carcinomas, while a marked pleomorphism could also be seen. Most carcinomas had more than three mitoses per 10 HPFs, ranging from 3 to 13.3 When the cell proliferative index Ki-67 is ≥4%, it can represent a statistically significant difference in the diagnosis of malignant tumor. Distant metastasis occurs in most myxoid adrenocortical carcinomas to liver, lung and other organs which provide the most reliable evidences for determining the properties and the malignant levels of tumors.3 Therefore, the differential diagnosis between adenoma and carcinoma depends on the aggregate analysis of clinical features, pathological findings and immunohistochemical results. The differential diagnosis includes chordoma, metastatic adrenal carcinoma and mesenchymal tumor with myxoid changes.4,5 The prognosis of myxoid adrenocortical adenoma is similar to general nonfunctional adrenocortical adenoma. Brown et al3 indicated that the prognosis between myxoid adrenocortical adenoma and myxoid adrenocortical carcinoma were obviously different (the five year survival rate of the former was 100%, while the later was only 50%). In our report the tumor was approximately 60 mm in diameter and weighted 83 g. Neither tumor necrosis nor capsular and vascular invasions was found under light microscopy. Immunohistochemical staining revealed that the tumor cells were positive for melan-A, inhibin-α, synaptophysin, vimentin and calretinin. They were negative for S-100 and AE1/AE3, while their Ki-67 was below 1%. All of these supported the diagnosis of myxoid adrenocortical adenoma. Neither recurrence nor metastasis was detected during follow-up for the subsequence 12 months.

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