Pathology International 2011; 61: 42–46
doi:10.1111/j.1440-1827.2010.02613.x
Case Report
Unusual double pituitary adenoma: A case report
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Fabio Rotondo1, Nasima Khatun2, Bernd W. Scheithauer3, Eva Horvath2, Thomas R. Marotta4, Michael Cusimano2 and Kalman Kovacs2 Department of 1Laboratory Medicine, 2Neurosurgery, and 4Medical Imaging, St. Michael’s Hospital, University of Toronto, Toronto, Ontario, Canada and 3Department of Pathology, Mayo Clinic, Rochester, Minnesota, USA
We report the case of a 60-year-old woman with Cushing disease. Magnetic resonance imaging (MRI) revealed a large sellar and suprasellar mass involving the right cavernous sinus, consistent with pituitary macroadenoma. It was resected by transsphenoidal surgery. Light microscopy revealed two separate pituitary adenomas with different histologic and immunohistochemical features. One was amphophilic and strongly Periodic Acid-Schiff (PAS) positive, the other chromophobic and PAS negative. The former tumor was immunopositive for adrenocorticotropic hormone (ACTH); approximately 30% tumor cells were immunopositive for MGMT (O6-Methylguanine-DNA MethylTransferase). The second tumor was a PAS negative, luteinizing hormone (LH) and alpha subunit immunopositive gonadotroph adenoma. In this tumor, about 90% of the cells were immunopositive for MGMT. The Ki-67 nuclear indices of the two tumors were 6% and 2%. Our case represents a rare combination of two morphologically different pituitary adenomas, one producing ACTH and the other LH and alpha subunit. The two tumors differed not only in Ki-67 labeling indices but in MGMT immunoexpression as well. Key words: Cushing disease, double adenoma, MGMT, pathology, pituitary adenoma
INTRODUCTION Pituitary adenoma is the most common tumor type of the sellar region.1–3 Most of the adenomas are benign, solitary, monoclonal slow–growing neoplasms. They may be associated with hormone excess. In clinical practice, concurrent Correspondence: Fabio Rotondo, B.Sc., BRT, St Michael’s Hospital, Department of Laboratory Medicine, Division of Pathology, 30 Bond St., Toronto, ON, Canada M5B 1W8. Email:
[email protected] Received 30 May 2010. Accepted for publication 10 September 2010. © 2010 The Authors Pathology International © 2010 Japanese Society of Pathology and Blackwell Publishing Asia Pty Ltd
double or multiple pituitary adenomas of differing types are rarely recognized. Their small size complicates their recognition clinically, surgically and morphologically. Therefore, the real incidence of multiple adenomas in surgical material may be underestimated.4,5 The reported incidence of double or multiple adenoma in surgical specimens is 0.37%4 and in autopsy pituitaries, it is approximately 0.9%.4,5 Despite its low frequency, adenoma multiplicity may be the cause of surgical failure. Careful histological and immunohistochemical assessment as well as ultrastructural study can confirm the presence of double pituitary adenomas. Pituitary adenomas obtained postmortem differ from those in surgical series in the form of adenoma types, functional status and biological behavior.6 Usually it is easy to distinguish double adenomas in autopsy material which are seen as discrete nodules.6 However, their identification may be difficult in surgically resected material.7 When, on rare occasions, preoperative clinical, laboratory findings and magnetic resonance imaging (MRI) suggest double adenoma, careful surgical exploration is necessary to avoid the loss of the second lesion. At present, pituitary tumors are classified mainly on the basis of size, hormonal activity, laboratory findings, histologic features, immunophenotype and ultrastructure.1–3 Herein, we describe an unusual example of double adenoma in a patient with Cushing disease.
CLINICAL SUMMARY A 60 year-old Asian woman with Cushing disease and a pituitary macroadenoma was admitted to St Michael’s Hospital, Toronto, Canada. She had previous history of hypertension, type 2 diabetes, pancreatic cyst and ductal carcinoma in situ of the breast treated with radiation and tamoxifen. The patient had also undergone hysterectomy and bilateral oophorectomy for uterine leiomyoma and menorrhagia 14 years prior. Laboratory measurement upon admission included: Potassium: 3.4 mmol/L (3.5–5.0 mmol/ L); Random glucose: 14.0 mmol/L (4.0–7.8 mmol/L); Serum
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Figure 1 (a) Sagittal localizing image as a reference for location of coronal views b–d. (b) Coronal T2 showing complex sellar mass with right cavernous extension. (c,d) Coronal pre and post Gad T1. Bright focus pre Gad (hemorrhage suspected); variable enhancement in mass post Gad. (e,f) Sagittal pre and post Gad T1. As above. Post Gad shows non-enhancing ‘halo’ around presumed area of hemorrhage.
cortisol (3:40 pm): 1600 nmol/L (193–690 nmol/L); Growth hormone (GH): 0.8 mg/L (5 mg/L); Insulin-like growth factor (IGF-1): 61 mg/L (96–243 mg/L); adrenocorticotropic hormone (ACTH): within 9–12 pmol/L (0–18 pmol/L); thyroid stimulating hormone (TSH): 1.07 mg/L (0.40–5.50 mg/L); follicle stimulating hormone (FSH): 43.2 mlU/mL (5–20 mlU/mL); luteinizing hormone (LH): 13.3 mlU/mL (5–25 mlU/mL); 24 h urinary free cortisol: 191 nmol/dL (50–220 nmol/dL), midnight salivary cortisols were less than 5 nmol/L, dexamethasone suppression test, 8 a.m. cortisol was 364 and she did not suppress after 1 or 2 mg of dexamethasone and ACTH levels were in the 9–12 range. Magnetic resonance imaging (MRI) revealed a large sellar complex and suprasellar mass mea-
suring approximately 2.6 ¥ 2.0 ¥ 1.4 cm associated with right cavernous sinus invasion. (Fig. 1a–c,e) A volumetric contrast-enhanced axial computerized tomography (CT) image showed a large tumor measuring 2.5 ¥ 2.1 ¥ 1.4 cm. The third ventricle was normal. The mass was removed by transsphenoidal surgery. Based on the clinical and laboratory findings, the diagnosis of Cushing disease due to ACTH secreting pituitary adenoma was made. PATHOLOGICAL FINDINGS Macroscopically, the mass consisted of several fragments of yellow tan to brown hemorrhagic soft tissue. Light microscopic
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Figure 2 (a,b) Periodic Acid-Schiff (PAS) stain showing cytoplasmic positivity in Adrenocorticotropic hormone (ACTH) adenoma (Fig. 2a), Original magnification: 200¥, and negativity in luteinizing hormone (LH) and alpha subunit adenoma (Fig. 2b). Original magnification: 200¥.
Figure 3 (a,b) ACTH immunostain showing cytoplasmic immunopositivity for ACTH in the first tumor. (Fig. 3a) Original magnification: 400¥. In the second tumor the cells are immunopositive for LH (Fig. 3b) Original magnification: 200¥.
examination revealed two separate pituitary adenomas showing different histologic and immunohistochemical features. One adenoma, which invaded the cavernous sinus, was amphophilic, strongly Periodic Acid-Schiff (PAS) positive. (Fig. 2a) The other tumor was chromophobic and PASnegative. (Fig. 2b) No significant cellular or nuclear pleomorphism was noted, and mitotic figures were rare in both tumors. Immunohistochemistry (streptavidin-biotin-peroxidase complex method) demonstrated cytoplasmic immunopositivity for ACTH in the amphophilic tumor. (Fig. 3a); this tumor was immunonegative for GH, prolactin (PRL), TSH, FSH, LH and alpha subunit. (Fig. 3b) The second tumor was immunopositive for LH and alpha subunit and immunonegative for the remaining adenohypophysial hormones. In one fragment, the two different adenomas were adjacent to each other. The Ki-67 nuclear labeling index using the MIB-1 antibody was 6% in the ACTH and 2% in the LH and alpha subunit immunopositive tumor. Antibody sources, clonality and dilutions are
outlined in Table 1. Immunostaining for O6-methylguanineDNA methyl transferase (MGMT), a DNA repair enzyme, showed 30% immunopositive cell nuclei in the ACTH immunopositive tumor and 90% in the LH and alpha subunitproducing adenoma. (Fig. 4a,b) Ultrastructurally, the ACTH immunopositive adenoma consisted of small, densely granulated, somewhat round to polygonal cells. The ovoid or slightly irregular nuclei contained a small nucleolus and small to moderate quantities of heterochromatin. The rough endoplasmic reticulum was moderately developed, and free polyriboses were abundant. The Golgi region contained forming as well as fully developed secretory granules, which were spherical to notched and measured 160 to 322 nm (mean: 220 nm). Many tumor cells contained bundles of perinuclear intermediate filaments. The portion of this tumor that invaded the cavernous sinus consisted of ACTH cells, but differed in being composed of larger, heavily granulated cells exhibiting ovoid, euchromatic nuclei and often multiple nucleoli and scant, thin
© 2010 The Authors Pathology International © 2010 Japanese Society of Pathology and Blackwell Publishing Asia Pty Ltd
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Primary antibodies used in immunohistochemical analysis
Antibody Growth hormone (GH) Prolactin (PRL) Adrenocorticotropic hormone (ACTH) Thyroid stimulating hormone (TSH) Follicle stimulating hormone (FSH) Luteinizing hormone (LH) ALPHA SUBUNIT MIB-1 MGMT
Vendor
Detail
Antigen retrieval
Dilution
Results
Dako Immunotech Dako Dako Dako NIDDK-NIH Biogenex Neomarker Invitrogen
Polyclonal Polyclonal Polyclonal Monoclonal Monoclonal Polyclonal Monoclonal Monoclonal Monoclonal
No No No No No No No Yes Yes
1:400 1:1000 1:1000 1:50 1:50 1:500 1:50 1:50 1:50
Negative Negative Positive Negative Negative Negative Negative Positive Positive
DISCUSSION
Figure 4 (a) MGMT (O6-Methylguanine-DNA Methyl-Transferase) immunostaining of the ACTH immunopositive tumor showing mostly low level MGMT immunopositivity. Original magnification: 250¥. (b) In the LH and alpha subunit immunopositive tumor, MGMT (O6Methylguanine-DNA Methyl-Transferase) immunostaining exhibited high-level MGMT immunopositivity. Original magnification: 250¥.
bundles of intermediate filaments in a minority of cells. The LH and alpha subunit immunopositive tumor was not represented in the electron microscopic specimen. Postoperatively, serum cortisol levels decreased and an MRI showed no residual tumor. (Fig. 1d,f)
Double pituitary adenomas are defined as two histologically, immunohistochemically and ultrastructurally distinct tumors occurring simultaneously.4,5,7–9 Such tumors differ from plurihormonal pituitary adenomas in which a single adenoma produces two or more, biochemically unrelated pituitary hormones.1–3,10 Immunohistochemistry is key to recognizing double adenomas in the pituitary. On the basis of immunopositivity, double pituitary adenoma combinations can be divided into three main patterns:4,5 GH-PRL-TSH producing adenomas accompanied by FSH and LH producing adenomas; GH-PRL-TSH producing adenomas accompanied by ACTH producing adenomas and ACTH producing adenomas accompanied by FSH and LH producing adenomas. Most frequent are GH-PRL-TSH producing adenoma accompanied by FSH and LH producing adenoma. Our case represents a combination of ACTH producing adenoma accompanied by LH and alpha subunit producing adenoma. About 1.6–3.3% of patients with Cushing disease have double or multiple pituitary adenomas.11,12 Most of the patients with Cushing disease, hypercortisolism is due to ACTH hypersecretion by pituitary adenoma cells. Hypersecretion of ACTH also occurs in ectopic corticotroph adenomas located in the parasellar region or the neurohypophysis.13 Extrapituitary tumors can also produce ACTH and corticotropin-releasing hormone (CRH).14–16 In our patient, high preoperative cortisol levels normalized after removal of the pituitary tumors, confirming them as the cause of ACTH hypersecretion. The ACTH producing tumor was invasive, with increased Ki-67 nuclear labeling index. It was an intriguing finding that MGMT immunoexpression differed also between the two tumors. Temozolomide therapy has become an option in the management of aggressive pituitary tumors.17–21 The effect of temozolomide on pituitary adenoma and carcinoma can be predicted based on MGMT immunopositivity.22–24 When MGMT levels are low, temozolomide can cause dramatic tumor shrinkage.17,23 In our case, the ACTH immunopositive tumor invaded the cavernous sinus and about 70% of the tumor cells were immunonegative for MGMT suggesting that this tumor would respond to
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temozolomide therapy. In contrast, the LH and alpha subunit immunopositive tumor exhibited high-level MGMT immunopositivity, making it unlikely to be affected by temozolomide administration. Clinical management of double pituitary adenomas requires not only a careful diagnostic approach but also the assessment of MGMT expression.24,25 Regarding double and multiple pituitary adenomas several questions are unresolved. The pathogenesis of double pituitary adenomas is not known. It may be that two different cell types transform to neoplastic cells and develop two different adenomas with no causal link. Alternatively, it is possible that cells of one adenoma transdifferentiates to another cell type and produces another adenoma. Molecular/genetic studies may provide new insights in the understanding of their development and progression.
ACKNOWLEDGMENTS The authors are grateful to the Jarislowsky and Lloyd CarrHarris Foundations and Mrs Sandra Sturino of the Canadian Italian Business Professional Ladies Auxillary Foundation for their generous support. We are also very much indebted to Ms. Corinne Holubowich for the literature search.
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