Case Report Myxoid variant of adrenocortical carcinoma: Report of a unique case
Rooshdiya Z. Karim,1 Edward J. Wills,1,2 Stanley W. McCarthy1 and Richard A. Scolyer1
1Department of Anatomical Pathology, Royal Prince Alfred Hospital, Camperdown and 2 Electron Microscopy Unit, Concord Repatriation General Hospital, Concord, New South Wales, Australia
Myxoid variant of adrenocortical carcinomas (ACC) are rare, there being only 11 cases in the literature to date. Reported herein are the findings of a case, which in contrast to all previously reported myxoid ACC, was devoid of typical non- myxoid areas. The patient was a 61-year-old man in whom a left adrenal mass was detected during investigation of Cushing’s syndrome. The adrenal was replaced by malig- nant cells and expanses of myxoid material. The cells were positive for melan-A, synaptophysin, vimentin and a- inhibin. The ultrastructural features of the cells were typical of adrenal cortical differentiation. The differential diagnosis of myxoid ACC includes extraskeletal myxoid chondro- sarcoma, chordoma, myxoid adenocarcinoma, myxoma, lipomatous tumors, nerve sheath tumors, smooth muscle tumors, gastrointestinal stromal tumor and other sarcomas. The presence of myxoid material in a retroperitoneal lesion raises a broad differential diagnosis in which myxoid adrenocortical neoplasms should be included. Clinicoradi- ological correlation may be helpful, but special stains, immunohistochemistry and ultrastructural examination may be necessary to establish the diagnosis.
Key words: adrenal gland, adrenocortical carcinoma, myxoid adrenocortical carcinoma, pathology
Although myxoid variant of adrenocortical carcinomas (ACC) is rare,1,2 there being only 11 cases reported in the literature to date,3-6 they should be considered in the differential diag- nosis of unusual myxoid neoplasms, particularly those occur- ring in intra-abdominal sites.
Myxoid ACC are characterized by the presence of abun- dant extracellular Alcian-blue-positive myxoid material. The malignant cellular component in the reported cases has vary- ing morphologies with glandular foci, cords, sheets and/or
single cells scattered in the myxoid material. Areas of typical ACC assist in establishing the diagnosis. The clinical, immu- nohistochemical and ultrastructural profile of myxoid ACC is similar to that of typical ACC.
The differentiation of ACC from adrenocortical adenoma, pheochromocytoma and metastases can be difficult. The abundant myxoid material in myxoid ACC broadens the differential diagnosis to include extraskeletal myxoid chon- drosarcoma, chordoma, myxoid carcinoma, myxoma, lipomatous tumors, nerve sheath tumors, smooth muscle tumors, gastrointestinal stromal tumors and other sarcomas that may include epithelioid cells in a myxoid matrix. Special stains, immunohistochemistry and ultrastructural examina- tion may be warranted due to the variety of histological appearances and the lack of diagnostic profile for many of the lesions included in the differential diagnosis. Myxoid adrenocortical adenomas have also been reported and the criteria for their differentiation from myxoid ACC are similar to those used for the non-myxoid types.
We report the light microscopic, immunohistochemical and ultrastructural findings of another case of this unusual neoplasm, which to our knowledge is only the third with ultrastructural assessment. Unlike all previously reported examples, areas of typical ACC were absent, despite exten- sive sampling. Immunohistochemistry and electron micros- copy were necessary to establish the diagnosis.
CLINICAL SUMMARY
A 61-year-old man was found to have a left adrenal mass during investigation of Cushing’s syndrome. He presented with a 5 month history of changing appearance (centripetal obesity, hair loss and skin changes), peripheral edema and abnormal glucose tolerance. There was also a recent onset of left flank pain. Repeated random cortisol levels were significantly elevated at 1042-1295 nmol/L (normal range 100-690 nmol/L). Serum adrenocortical releasing hormone
Correspondence: Rooshdiya Z. Karim, MB BS, Department of Ana- tomical Pathology, Royal Prince Alfred Hospital, Central Sydney Area Health Service, Missenden Road, Camperdown, NSW 2050, Australia. Email: rooshdiya@yahoo.com.au
Received 19 June 2005. Accepted for publication 18 October 2005.
(ACTH), follicle stimulating hormone (FSH), luteinizing hormone (LH) and testosterone were suppressed. No metastases were identified on bone scan or computed tomography (CT) scan. His medical background included a right orchidectomy followed by postoperative radiotherapy for seminoma 20 years previously, and degenerative spinal joint disease with crush fractures.
At operation a large bosselated left adrenal mass was removed. It did not appear to involve the renal vein or adja- cent structures, and was diagnosed as an ACC on histolog- ical features. The spleen sustained a capsular tear and a splenectomy was performed. He recovered well and was discharged 7 days postoperatively with a normal serum cor- tisol level.
He re-presented 12 months later with recurrent Cush- ing’s syndrome and a CT scan revealed a mass suspicious for local recurrence. Further imaging showed over 20 lung lesions and several liver lesions suggesting metastases. He was given mitotane with no clinical response. He remained Cushingoid with elevated urinary and serum cortisol levels but otherwise symptomatically well until 15 months further follow up. He then deteriorated over the next 4 months with increasing symptoms related to the Cushing’s (fatigue, vertebral crush fractures due to osteoporosis, myopathy) and died 43 months after initial presentation from pneumonia.
PATHOLOGICAL FINDINGS
Macroscopic findings
The adrenal mass was 100x 90 × 60 mm and weighed 192.8 g. On serial slicing there was a poorly circumscribed, vaguely lobulated tumor with infiltration of adjacent adipose tissue (Fig. 1). No normal adrenal tissue was identified. The cut surface was heterogenous with tan, yellow, hemorrhagic and necrotic areas. One block per cm of tumor was taken.
The spleen weighed 193.7 g and was unremarkable except for a 55 x 30 mm area where the capsule was torn.
Microscopic findings
The adrenal gland was virtually replaced by a malignant neoplasm composed of polygonal cells arranged in sheets, strands and cords (Fig. 2). There was a vaguely lobular pat- tern with peripheral clustering of cells and large central hypo- cellular expanses of Alcian-blue-positive myxoid material (Figs 3,4). Patchy areas of necrosis were also present. No chondroid differentiation was seen. There was atrophic adre- nal cortex present at the periphery of the tumor in some sections (Fig. 4).
The cells were small with hyperchromatic oval nuclei, inconspicuous nucleoli and eosinophilic cytoplasm (Fig. 5). The cells in the myxoid pools were vacuolated and arranged in cords and cribriform patterns. Frequent mitoses were present, >25 mitoses/50 high power fields (HPF), and included atypical forms (Fig. 5). There was focal infiltration of periadrenal adipose tissue and extra-adrenal vessels (Fig. 2). The tumor would be designated as a high-grade adrenocortical carcinoma using the Weiss criteria.1 It has >20 mitoses/50 HPF, atypical mitoses, capsular invasion, size of ≥10 cm, necrosis, high ‘Fuhrman grade’ cytology, loss of nesting and clear cells and vascular invasion.
Immunohistochemical findings
Formalin-fixed, paraffin-embedded tissue was also stained immunohistochemically using the labeled polymer alkaline phosphatase method (Dako Envision kit, DakoCytomation, Carpinteria, CA, USA). The chromogens used were diami- nobenzidine (brown) and basic fuschin with napthol-AS-B1- phosphate (red). The antibodies used are listed in Table 1. The cells were strongly positive for melan-A, synaptophysin, vimentin and a-inhibin (Fig. 6). The cells were negative for
| Anti- | Antibody clone | Dilution | Antigen retrieval | Source |
|---|---|---|---|---|
| Melan-A | A103 | 1:50 | Pressure cooker (EDTA) | DakoCytomation (Carpinteria, CA, USA) |
| Synaptophysin | Affinity isolated | 1:100 | Pressure cooker (citrate) | DakoCytomation |
| Vimentin | V9 | 1:100 | Microwave (EDTA, Tris, citrate pH 8.0) | DakoCytomation |
| a-Inhibin | R1 | 1:100 | Pressure cooker (citrate) | Serotec (Oxford, UK) |
| Desmin | D33 | 1:50 | Microwave (EDTA, Tris, citrate pH 8.0) | DakoCytomation |
| S-100 protein | Polyclonal | 1:500 | None | DakoCytomation |
| Cytokeratin | AE1/AE3 | 1:100 | Protease digest (Proteinase K) | DakoCytomation |
| LMWCK | Cam5.2 | 1:100 | Protease digest (Proteinase K) | Novocastra (Newcastle upon Tyne, UK) |
| HMWCK | 34ßE12 | 1:100 | Protease digest (Proteinase K) | DakoCytomation |
| CD117 | 1:100 | Pressure cooker (citrate) | DakoCytomation | |
| Somatostatin | 1:250 | Nil | DakoCytomation |
EDTA, ethylenediamine tetra-acetic acid; HMWCK, high-molecular-weight cytokeratin; LMWCK, low-molecular-weight cytokeratin.
₹
a
b
S-100 protein, keratins (stained by AE1/AE3, Cam5.2, 34ßE12), CD117 and somatostatin.
Electron microscopy
Material retrieved from formalin was fixed in glutaraldehyde buffered with sodium cacodylate and processed for electron microscopy after postfixation in osmium tetraoxide. The tumor was composed predominantly of steroid secreting cells characterized by abundant smooth endoplasmic reticu- lum in anastomosing tubules, forming occasional lamellar whorls. There was sparse short stacks of rough endoplas- mic reticulum, mitochondria with tubulovesicular cristae and lipid droplets (Figs 7,8). Considerable variation in the rela- tive proportions of these organelles was seen from cell to
cell. No endocrine granules were identified. The extracellular matrix contained profuse proteoglycan particles, as well as flocculent and fibrillar material, and membranous debris (Figs 7,8).
DISCUSSION
ACC is a rare tumor with an incidence of two cases per million population per year.1,2 Although foci of myxoid change are occasionally observed in ACC, predominantly myxoid adrenal cortical neoplasms are extremely rare.2 To our knowl- edge, only 11 myxoid ACC and eight myxoid adrenal ade- nomas have been reported in the English-language literature to date (Table 2).3-8 Myxoid ACC was first reported in 1979
by Tang et al. with the second case reported by Forsthoefel in 1994.3,4 Brown et al. reported the first series of adrenal cortical myxoid neoplasms in 2000 with six adenomas and eight ACC.5 Honda et al. reported the first case of myxoid adrenocortical adenoma in Japan in 2001.7 Two unusual myx- oid adrenal cortical neoplasms were reported in 2003: an adenoma with a pseudoglandular and myxoid architecture by Dundr and Novak and a myxoid ACC with lipomatous meta- plasia by Izumi et al.6,8 The present case is the third reported in which ultrastructural features are documented and, in con- trast to all previous reported examples, it was devoid of typical non-myxoid areas of ACC.
Although all ages are affected, ACC most frequently occurs in older individuals in the fifth-seventh decades, with a slight female preponderance.1,2 In the cases of myxoid
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| Case (ref no.) | Age/ sex | Weight (g)/ diameter (cm) | Necrosis | Mitoses | Vascular/ capsular invasion | Follow up | Last known status |
|---|---|---|---|---|---|---|---|
| 1 (3) | 41/F | -/9 | – | None | None/- | 15 months | AWD |
| 2 (4) | 45/M | 900/17.5 | Present | 1-4/50 HPF | Present/None | 3 years | DOD |
| 3 (5) | 44/F | 180/9 | None | 4/10 HPF | None/None | 27 months | Alive |
| 4 (5) | 48/M | 151.9/7.7 | Present | 7/10 HPF | None/Present | – | – |
| 5 (5) | 43/F | 65/8 | None | 6/10 HPF | None/Present | 13 months | AWD |
| 6 (5) | 48/M | 195/9 | None | 5/10 HPF | Present/Present | 40 months | DOD |
| 7 (5) | 53/F | 138/8.4 | Present | 13/10 HPF | None/Present | 29 months | DOD |
| 8 (5) | 51/M | 700/16 | Present | 5/10 HPF | Present/Focal | 14 months | DOD |
| 9 (5) | 63/F | -/11 | Present | 9/10 HPF | None/Present | 5 months | DOD |
| 10 (5) | 56/F | 470/10 | Present | 3/10 HPF | Present/None | 3 months | AWD |
| 11 (6) | 38/M | 380/13.5 | None | Not counted | Present/Present | 7 weeks | AWD |
| 12 (Present case) | 61/M | 192.8/10 | Present | >25/50 HPF | Present/Present | 43 months | DOD |
ACC, adrenocortical carcinoma; AWD, alive with disease; DOD, dead of disease
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ACC reported to date there is a similar age range (38-63 years).3-7 Although Brown et al. found a female pre- ponderance in both malignant (5:3) and benign myxoid adre- nal tumors (5:1),5 to date the total cases of myxoid ACC (including the current case) have been equally distributed between male and female patients.3-6 All reported patients with myxoid ACC have had elevated serum hormone levels including cortisol, aldosterone, ACTH, FSH and/or LH.3-6 The majority clinically manifested as Cushing’s syndrome. Typical and myxoid ACC each have a similar poor prognosis of 70- 90% mortality. Early metastasis often occurs, especially to lung and liver.3-6 However, the biological behavior of individ- ual tumors is difficult to predict from histological features.2
As is the case for many endocrine neoplasms, differentia- tion of benign from malignant adrenal tumors is very diffi-
cult.1,2,9,10 Criteria proposed by Weiss in 1984 and restudied in 1989 are most often used and include assessment of nuclear grade, mitotic rate, predominance of lipid-depleted compact cells, diffuse architecture, necrosis, invasion of sinu- soids and invasion of the capsule.10,11 High mitotic rate (>5/ 50 HPF), atypical mitoses and invasion of vessels were found only in metastasizing or recurring adrenal cortical tumors.10 A study by Evans and Vassilopoulou-Sellin of 56 adrenal cortical neoplasms with a minimum of 5 years follow up found that carcinomas were characterized by at least 4 mitoses/ 10 HPF, a lack of nested growth pattern, a dominance of compact eosinophilic cells and tumor necrosis.12 Malignant adrenal cortical neoplasms tended to be larger and heavier than their benign counterparts.1,2,9,10 The criteria used for differentiation of myxoid adrenal cortical adenomas from myxoid ACC are similar. The present case had abundant mitoses (including atypical forms), necrosis, compact eosino- philic cells, high-grade nuclei and, most importantly, invasion into vessels and extra-adrenal fat. In view of these features a diagnosis of carcinoma was made at the time of resection and was supported by the subsequent development of assumed metastases.
The myxoid material in myxoid variants of ACC has been shown to be Alcian-blue-positive (sensitive to digestion with hyaluronidase), but negative with diastase-periodic acid- Schiff (PAS) and mucicarmine stains, consistent with connective tissue mucin.3-8 Previous ultrastructural studies merely described the myxoid areas as free of any structures3 or as acellular myxoid material,5 but in the present case abundant proteoglycan particles, as well as flocculent and fibrillar material, were demonstrated. The sig- nificance of the myxoid material and its mechanism of production remain uncertain. Forsthoefel suggested that it represents a degenerative phenomenon or is produced by stromal fibroblasts.4 However, stromal fibroblasts are too sparse in these tumors to account for the large volumes of myxoid material present. Honda et al. postulated that in view of their mesodermal origin the adrenal cortical cells might be producing the myxoid material.7 No intracellular myxoid material was demonstrated by special stains or electron microscopy in either their case7 or in the present case. Forsthoefel also hypothesized that the myxoid material could be related to functional status, postulating that hor- monally inactive tumors would be lipid depleted and rich in myxoid material.4 The cases described since Forsthoefel’s report in 1994 do not support this theory because several hormonally active tumors with >70% myxoid areas have been reported.3,8 The present case is one such tumor with extensive myxoid change, clinically manifest Cushing’s syndrome, high serum cortisol levels, and ultrastructural evidence of active hormonal production.
All myxoid ACC reported previously have contained areas of histologically typical ACC that have assisted in making the
diagnosis.1-5,8,9 No such areas were present in the current case despite extensive sampling. Immunohistochemical stains may also assist in establishing the diagnosis of ACC, particularly in those tumors lacking the typical histological features or which are unassociated with serum hormone production. ACC are characteristically positive for vimentin, neuroendocrine markers, melan-A and a-inhibin. Positivity for these markers may assist in their identification.1,2,5-9 There have been considerable differences in the reported immu- noreactivity for epithelial markers in ACC with many, including the present case, reporting negative results with cytokeratin and epithelial membrane antigen (EMA).1,2,5-7,9,13 These differences may be related to variations in immunohisto- chemical staining techniques, such as the method of antigen retrieval used. Postive immunohistochemical staining with antibodies detecting cytochrome P45011 would support adrenocortical origin because this cytochrome is present in mitochondria of streoid cells of the adrenal cortex.14 Similarly immunohistochemistry can detect transcription factors involved in steroidogenesis such as AD4BP/SF-1, whose target genes include DAX-1 and CYP11B1.15 McCluggage et al. reported consistent immunoreactivity for a-inhibin mon- oclonal antibody in normal adrenal cortex, hyperplastic lesions, and benign and malignant adrenal cortical tumors.13 Other primary adrenal neoplasms, including pheochromocy- toma are negative with a-inhibin.13 Negative melan-A immu- noreactivity in pheochromocytoma also assists in the differential diagnosis. Ultrastructural studies in two previous myxoid ACC showed the typical features of steroid hormone producing cells with well-developed smooth and rough endo- plasmic reticulum, scattered lipid droplets and mitochondria, and are characteristic of steroid hormone production.1-3,5 These characteristics, although not evident in every tumor cell, were nevertheless readily demonstrable in the present case and contrasted with the lack of typical histology. Poor correlation between light and electron microscopy may also be evident in typical ACC, although usually in the reverse direction. Approximately one-third of all ACC studies by Mackay et al. failed to show ultrastructural evidence of steroid cell differentiation.16
The differentiation of ACC from adrenal cortical adenoma and pheochromocytoma can be difficult and, as discussed here, may be established by the use of appropriate immuno- histochemistry and electron microscopy. Although the mech- anism of production is unknown, the significance of the myxoid material is that its presence broadens the differential diagnosis to include extraskeletal myxoid chondrosarcoma (ESMC), chordoma, myxoid carcinoma, myxoma, lipoma, liposarcoma, nerve sheath tumors, leiomyoma, leiomyosar- coma, gastrointestinal stromal tumor (GIST) and so-called ‘myxoid malignant fibrous histiocytoma’ (MFH). Clinicoradio- logical correlation is often helpful, particularly magnetic resonance imaging, because this may indicate the exact
anatomical location of the tumor and its relationship to other structures. The presence of myxoid material in a retroperito- neal lesion raises a broad differential diagnosis in which myxoid adrenocortical neoplasms should be included. Clini- coradiological correlation may be helpful, but special stains, immunohistochemistry and ultrastructural examination may be necessary to establish the diagnosis, particularly in those tumors lacking typical areas of adrenocortical differentiation, small biopsies, and when there is no clinical evidence of active adrenal hormone production. The variety of appear- ances and the lack of diagnostic profile for many of the lesions included in the differential diagnoses, including myx- oid ACC, are other reasons why a final diagnosis will usually require careful correlation of information.
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