Pituitary pathology in Cushing's disease

Granulation Patterns of Functional Corticotroph Tumors Correlate with Tumor Size, Proliferative Activity, T2 Intensity-to-White Matter Ratio, and Postsurgical Early Biochemical Remission

Unlike somatotroph tumors, the data on correlates of tumor granulation patterns in functional TPIT lineage pituitary neuroendocrine tumors (corticotroph tumors) have been less uniformly documented in most clinical series. This study evaluated characteristics of 41 well-characterized functional corticotroph tumors consisting of 28 densely granulated corticotroph tumors (DGCTs) and 13 sparsely granulated corticotroph tumors (SGCTs) with respect to preoperative clinical and radiological findings, tumor proliferative activity (including mitotic count and Ki-67 labeling index), and postoperative early biochemical remission rates. The median (interquartile range (IQR)) tumor size was significantly larger in the SGCT group [16.00 (16.00) mm in SGCT vs 8.5 (9.75) mm in DGCT, p = 0.049]. T2-weighted signal intensity and T2 intensity (quantitative) did not yield statistical significance based on tumor granulation; however, the T2 intensity-to-white matter ratio was significantly higher in SGCTs (p = 0.049). The median (IQR) Ki-67 labeling index was 2.00% (IQR 1.00%) in the DGCT group and 4.00% (IQR 7.00%) in the SGCT group (p = 0.043). The mitotic count per 2 mm2 was higher in the SGCT group (p = 0.001). In the multivariate analysis, the sparse granulation pattern (SGCT) remained an independent predictor of a lower probability of early biochemical remission irrespective of the tumor size and proliferative activity (p = 0.012). The current study further supports the impact of tumor granulation pattern as a biologic variable and warrants the detailed histological subtyping of functional corticotroph tumors as indicated in the WHO classification of pituitary neuroendocrine tumors. More importantly, the assessment of the quantitative T2 intensity-to-white matter ratio may serve as a preoperative radiological harbinger of SGCTs.

Prevalence and clinical characteristics of Crooke's cell adenomas in 101 patients with T-PIT-positive pituitary adenomas: Case series and literature review

PURPOSE

We aimed to perform a retrospective analysis of a rare subtype of corticotroph adenoma, Crooke's cell adenoma, to better understand its clinical features.

METHODS

We collected T-PIT-positive pituitary adenomas and screened Crooke's cell adenomas from January 2020 to December 2021 in our center. Case reports of such tumors were also collected through a literature search. Clinical data such as biochemical tests, imaging examinations, and pathological data of the above cases were analyzed.

RESULTS

A total of 101 T-PIT-positive patients were treated in our center in the last 2 years, and 4 were finally pathologically diagnosed with Crooke's cell adenomas. All of these patients were male with elevated adrenocorticotropic hormone levels, and 50.0% presented with hypercortisolemia, Cushing's syndrome, visual impairment, and headache. The tumor diameter was significantly larger in these 4 patients (37.0 mm) than in the other patients (26.0 mm), and their tumor invasive behavior was more pronounced. Cases reported in the literature were mainly female (72.8%), and the clinical presentation was also dominated by Cushing's syndrome (65.1%) and hormonal dysfunction. Tumors were more common as macroadenomas (33.2 mm) and suprasellar growths (63.8%). The tumor recurrence rate was as high as 55.6%, with 6 cases progressing to pituitary carcinomas and 7.7% of tumor-related deaths. Our further integrated analysis of our center and reported cases revealed that gender, Cushing's syndrome, visual dysfunction, hormonal disorders, and tumor growth characteristics were statistically different in different tumor categories.

CONCLUSION

Crooke's cell adenoma is a tumor subtype with obvious clinical aggressive behavior, and an in-depth analysis of its clinical characteristics may assist in developing a comprehensive treatment plan.

Gamma Knife Radiosurgery in Patients with Crooke Cell Adenoma

BACKGROUND

Crooke cell adenoma is a very rare subtype of pituitary neoplasm that is known to be clinically aggressive. These tumors can secrete adrenocorticotropic hormone or may be endocrinologically silent. We evaluated the effect of Gamma Knife radiosurgery (GKRS) on endocrine remission and tumor control.

MATERIALS AND METHODS

This study comprised 5 patients (2 men, 3 women; median age at GKRS, 55 years [range, 21-65 years]) with pathology-confirmed Crooke cell adenoma treated with GKRS at the Gamma Knife Center of the University of Virginia. The median time interval between transsphenoidal resection and GKRS was 5.8 months. The median margin dose was 25 Gy (range, 18-25 Gy). Median treated adenoma volume was 3.12 mL. Median follow-up was 107 months (range, 44-122 months).

RESULTS

Tumor control was achieved in all patients. Three patients achieved endocrine remission at the last follow-up. The median time interval to cortisol normalization when off of anti-hormone secreting medication was 12 months (range, 6-24 months). Newly developed or worsening endocrinopathy occurred in 3 patients at 6, 15, and 18 months, respectively. Cranial nerve III neuropathy developed in 1 patient. Two patients required bilateral adrenalectomy at 44 months and 50 months, respectively, following GKRS.

CONCLUSIONS

GKRS appears to be a safe and reasonably effective treatment option for Crooke cell adenoma. Multicenter studies with larger numbers of patients are needed to verify these findings.

The role of Crooke's changes in recurrence and remission after gamma knife radiosurgery

PURPOSE

The objective of this study is to evaluate the role of Crooke's changes (CC) in normal the peri-tumoral anterior pituitary gland, in patients with Cushing's disease (CD) with a histopathological confirmed corticotroph adenoma, and determine if there is any difference in the recurrence and remission rates in CD patients after treatment with Gamma Knife Radiosurgery (GKRS).

METHODS

All patients treated with GKRS for CD from 2005 to 2016 at our institution were identified. Patients had a confirmed adrenocorticotropic (ACTH)-secreting adenoma, i.e. corticotroph adenoma, and normal pituitary gland included in the surgical specimen, and specimens were stained with hematoxylin and eosin and also immunostaining for cytokeratin and ACTH. Statistical analyses were performed in a total of 61 patients who met the inclusion criteria. Additionally, we analyzed 20 patients in each group, with and without CC, after they were matched in a propensity score fashion.

RESULTS

Endocrine remission defined as, a normal 24 h urine free cortisol while off suppressive medication, occurred in 48 patients (78.7%), with 76.9% in those with CC and 81.8% in those without CC. There was no statistical significant difference between the two groups in regarding remission (p = 0.312) or recurrence (p = 0.659) in either the unmatched or matched cohorts.

CONCLUSION

The presence or absence of CC in normal pituitary gland does not appear to confer a lower rate of remission or a higher rate of recurrence after GKRS. Patients with pituitary corticotroph adenomas that present with CC features may be well served by Stereotactic radiosurgery (SRS).

Crooke's Changes In Cushing's Syndrome Depends on Degree of Hypercortisolism and Individual Susceptibility

CONTEXT

Although Crooke's changes in the pituitary corticotrophs were initially described in 1935, the prevalence in which the changes occur in patients with Cushing's syndrome (CS) has not been established.

OBJECTIVE

This study aimed to determine the prevalence and assess clinical features associated with the presence or absence of Crooke's changes in a large set of patients with CS.

DESIGN

Information from a prospective computer database and retrospective chart review was analyzed.

SETTING

The setting was an academic medical center.

PATIENTS

Consecutive patients (N = 213) who received surgery with a preoperative diagnosis of Cushing's disease are included.

INTERVENTION

The patients received pituitary surgery and specimens obtained underwent pathological analysis.

MAIN OUTCOME MEASURE

The presence or absence of Crooke's changes was determined by histopathological analysis of the normal pituitary tissue included with the specimen obtained at surgery. Cortisol production was measured by 24-hour urine cortisol production.

RESULTS

Crooke's changes occurred in 144 of 177 patients (81%) with a histologically demonstrated ACTH-staining tumor and in 74% of 213 patients diagnosed with CS who had pituitary surgery. The presence of Crooke's changes correlated with the finding of an ACTH-staining tumor removed at surgery and with the degree of hypercortisolism. Among patients with histologically established ACTH-staining tumors the prevalence of Crooke's changes was particularly high in patients with a 24-h urinary free cortisol (UFC) of at least 4-fold the upper limit of normal, in which 91% of patients had Crooke's changes, compared with 74% of patients whose maximum UFC was less than 4-fold the upper limit of normal (P = .008).

CONCLUSIONS

Crooke's changes occur in 75-80% of patients with CS, and depend on the degree of hypercortisolism and individual variability. Almost all patients with UFC at least 4-fold the upper limit of normal have them, whereas with less severe hypercortisolism the expression of Crooke's changes varies from person to person.

Cytokeratin CK20 is a sensitive marker for Crooke's cells and the early cytoskeletal changes associated with hypercortisolism within pituitary corticotrophs

Crooke's cells are nonneoplastic corticotroph cells found in the adenohypophysis of patients who have an endogenous or exogenous excess of glucocorticoids. Classic Crooke's cells have a prominent hyaline cytoplasmic ring that displaces the basophilic granules of the normal cell. This characteristic appearance is produced by a perinuclear accumulation of cytokeratin filaments. Immunohistochemistry for cytokeratins is a sensitive way to identify Crooke's cells, but a keratin antibody specific for Crooke's hyaline change has not been reported. Normal pituitary epithelial cells are variably reactive for many keratin antibodies but are negative for cytokeratin 20 (CK20) expression. We evaluated the use of CK20 immunohistochemistry as a marker for Crooke's cells. We examined sections from 25 pituitary glands resected from 15 patients who had undergone exogenous glucocorticoid administration and from 10 patients with an endogenous source of hypercortisolism; sections from 10 normal pituitary glands obtained at autopsy were used as controls. CK20 immunoreactivity was observed only in corticotrophs. A staining pattern consistent with classic Crooke's cells was seen in pituitary gland sections from 15 of the cases. Cells with less intense CK20 positivity were present in sections from all 25 cases. We found CK20 to be a sensitive and specific marker for Crooke's cells and also for the previously unrecognized, subtle, cytoskeletal changes that occur in corticotrophs in response to hypercortisolism.

[Pituitary gland tumors]

Pituitary adenomas must be clearly differentiated from other tumors of the sellar region (especially meningiomas, granular cell tumors, chordomas and germinomas), which may look very similar. The sub-classification of adenomas depends on the methods used, in particular the immunostaining for pituitary hormones. This sub-classification is not necessary in every case, but must be performed if unusual findings are observed during surgery or if surgery is unsuccessful and radiation or drug-therapy is planned. Special structures and non-immunohistochemical stainings are very helpful for typing adenomas. We differentiated monohormonal densely or sparsely granulated GH-cell adenomas, monohormonal sparsely or very rarely densely granulated prolactin cell adenomas, monohormonal densely or sparsely ACTH-cell adenomas, monohormonal TSH-cell adenomas and FSH/LH cell adenomas from bihormonal adenomas of mammosomatotroph or GH/prolactin cell type or of the acidophil stem cell adenoma type. The number of plurihormonal adenomas decreased with the use of improved monoclonal antibodies. Clinically inactive adenomas are classified as null cell adenomas, oncocytic adenomas or FSH/LH-cell adenomas. These appear as subtypes of one entity deriving from the gonadotroph cell type. Craniopharyngiomas are classified into adamantinous and papillary types, which are not only structurally but also clinically different. If adamantinous craniopharyngiomas show very strongly regressive changes, immunostaining for keratin may be necessary to identify the squamous epithelia for the demonstration of craniopharyngioma.

Juxtaposition of an ectopic corticotroph adenoma of the sphenoid sinus with orthotopic intrasellar corticotroph hyperplasia in a patient with Cushing disease. Case report

Ectopic pituitary adenomas (EPAs) are rare and their association with orthotopic corticotroph hyperplasia has not been published. The case of a 30-year-old woman with clinical and biochemical evidence of Cushing disease (CD) is reported. A magnetic resonance image obtained preoperatively revealed asymmetrical inhomogeneity of the pituitary gland, which was suggestive of localized adenoma. It also showed what was thought to be a small sphenoid polyp. Postoperatively the latter lesion was found to be an ectopic corticotroph adenoma. The pituitary gland, which was free from any tumor, exhibited diffuse unilateral corticotroph hyperplasia. Clinical, radiological, laboratory, and histopathological findings are presented. A review of the literature and a discussion of possible causes of this unique association between the ectopic corticotroph adenoma and the pituitary hyperplasia are provided.

Cushing's disease: a surgical view

The management of adrenocorticotropic hormone (ACTH)-dependent Cushing's disease implies difficulties in the differential diagnosis, in the detection of minute pituitary adenomas, as well as in the radical removal of invasive adenomas. Magnetic resonance imaging (MRI) is unspecific and often negative in minute adenomas of three or less millimeters diameter. The trias of detectable ACTH, suppression of cortisol in the high-dose dexamethasone test, and stimulation in the corticotropin-releasing-hormone (CRH)-test has a high accuracy to prove pituitary dependency. In unclear cases, the use of inferior petrosal sinus sampling (IPSS) or cavernous sinus sampling (CSS) for the exclusion of ectopic ACTH-syndrome is currently advised especially in cases where cranial MRI is negative. The reliability of these methods to localize the mostly lateralized microadenomas is still discussed. Transsphenoidal microsurgical adenomectomy, the accepted primary therapy of Cushing's disease, has been published from experienced pituitary centers with remission rates ranging from 70% to 98% in the last decade. False diagnosis (pseudo-Cushing, ectopic ACTH-syndrome), incorrect adenoma localization by IPSS or CSS, and the rate of minute or non-resectable invasive tumors influence the results. The handling of minute specimen implies problems for surgeon and pathologist. Intraoperative tumor localization was improved by ACTH measurement from the cavernous sinus and the adenoma itself, by cytology, and frozen sections. The histology of the anterior lobe (rate of Crooke's cells) bears information of clinical relevance. Invasive macroadenomas may deserve repeat microsurgery, medical treatment, and radiosurgery.

Metamorphosis of a non-functioning pituitary adenoma to Cushing's disease

Silent pituitary adenomas occur in 25-40% of all clinically apparent pituitary tumours. However, the subsequent development of florid Cushing's disease in a patient with a previous non-functioning tumour is extremely rare. We describe a 47 year-old woman presenting initially with a large, invasive and recurrent, non-functioning pituitary tumour. Histopathologic study of the initial tissue did not stain for any hormones. Six years after the initial presentation, she manifested florid ACTH dependent Cushing's syndrome. A recurrent invasive pituitary macroadenoma necessitated a third transphenoidal surgery. The resected specimen, in this instance, revealed positive staining for ACTH, FSH, prolactin, and growth hormone on immunocytochemistry. An incomplete response to surgical, radiation and medical therapy necessitated a bilateral adrenalectomy to control the hypercortisolism, which resulted in remarkable clinical improvement. We also review five previous case reports from the published literature of similar transformations from non-secreting pituitary adenomas to Cushing's disease. This subset of patients may represent yet another entity in the widening spectrum of Cushing's syndrome.

Expression of corticotropin-releasing hormone messenger ribonucleic acid in human pituitary corticotroph adenomas associated with proliferative potential

Among the factors that promote the growth of human pituitary corticotroph adenomas (hPCAs), the proliferative potential of CRH secreted by hPCAs on these tumors is not well known. In this study, the CRH messenger ribonucleic acid (mRNA) transcripts were demonstrated on paraffin sections using the quantitative in situ hybridization method in 37 of 43 hPCAs, including 17 of 22 microadenomas, 15 of 15 macroadenomas, and 5 of 6 locally invasive adenomas according to Hardy's classification of pituitary adenomas. The more important findings were that CRH mRNA signal intensity in pituitary corticotroph adenoma cells was linearly correlated with Ki-67 tumor growth fractions (r = 0.802; P < 0.0001), and in macroadenoma and locally invasive adenoma cells it was significantly higher than in microadenoma cells (P = 0.035). On the other hand, CRH mRNA transcript accumulation was absent or negligible in 10 normal pituitary glands (P = 0.005). This is the first report of the frequent expression of CRH mRNA localized in human pituitary corticotroph adenoma cells. These results indicate that CRH from a local source of corticotroph adenoma cells not only has autocrine/paracrine functions in corticotroph adenomatous tissue, but also is an important factor associated with a proliferative potential of hPCAs.

Failure of Partial Hypophysectomy as Definitive Treatment in Cushing's Disease Owing to Nodular Corticotrope Hyperplasia: Report of Four Cases

Nodular corticotrope hyperplasia is a rare pathology causing Cushing's syndrome owing to a primary pituitary disease or ectopic CRH production. In this study, we evaluated the laboratory and pathological findings and results of transsphenoidal pituitary surgery in four patients with Cushing's disease. Dynamic tests of pituitary-adrenal function (dexamethasone suppression, metyrapone, CRH, and DDAVP tests) were done before and after transsphenoidal pituitary surgery. Plasma and total urinary cortisol, serum 11-deoxycortisol, and plasma ACTH were determined by RIA. Hormonal dynamic tests and radiologic studies were compatible with a pituitary ACTH source. The transsphenoidal surgery revealed the presence of corticotrope hyperplasia confirmed by immunoperoxidase stain and a preserved reticulum framework in the removed pituitary tissue of these four patients. The pituitary surgery led to a short period of improvement in two of the patients (1 and 4), a 3-yr remission in one patient (patient 2), and no improvement in one (patient 3). We conclude that although our patients appear to have inadequate suppression with high-dose dexamethasone, there is no way to diagnose this pathology presurgically, and that total hypophysectomy, bilateral adrenalectomy, and irradiation are the only alternatives for definitive treatment. A CRH-secreting ectopic tumor could not be found in our patients either before or after surgery in the follow-up period.

Cushing's disease in a child caused by a corticotropin-releasing hormone-secreting intrasellar gangliocytoma associated with an adrenocorticotropic hormone-secreting pituitary adenoma

Cushing's disease resulting from intrasellar corticotropin-releasing hormone (CRH)-secreting gangliocytomas is very rare, and only two such cases have been reported in the literature to date. The authors present a third case in which an adrenocorticotropic hormone-secreting pituitary adenoma was found in addition to a gangliocytoma in a 10-year-old girl with clinical and endocrinological symptoms of Cushing's disease. Computed tomographic and magnetic resonance imaging scans showed a suprasellar and parasellar tumor. A green-colored, heterogeneous tumor and a small adenoma were removed transsphenoidally. Histological examination revealed a large gangliocytoma immunoreactive for CRH and a small, mucoid cell pituitary adenoma immunoreactive for ACTH. This is the first case of such a tumor causing Cushing's disease in a child. It might exemplify induction of an ACTH-secreting pituitary adenoma by means of chronic overstimulation of CRH.

Effect of drugs on pituitary ultrastructure

Various drugs and hormones influence the light microscopic and especially the electron microscopic structure of the anterior pituitary and its tumors. Many structural effects are known only from animal experiments since specimens from human pituitaries are mostly not available. The structure of growth hormone (GH) cells is relatively stable. A massive GH cell hyperplasia is known only in rare cases with growth hormone releasing factor (GRF) excess from tumors. Prolactin cells can be stimulated by drugs, neurotransmitters, and hormones which decrease the dopamine inhibition. Adrenocorticotropic hormone (ACTH) cells are stimulated by stress, some hormones, loss of adrenals, and drugs which activate the alpha 1- and beta-receptors or inhibit the alpha 2-receptors. They are suppressed and changed into Crooke's cells by treatment with glucocorticoids. Thyroid-stimulating hormone (TSH) cells increase in number and size in states for overstimulation especially by thyrotropin releasing hormone (TRH). A decrease results from hyperthyroidism and possibly from somatostatin, L-dopa, and dopamine. Gonadotroph cells transform into castration cells in strongly hyperactive states (gonadectomy, antiandrogens, gonadotropin releasing hormone [Gn-RH]agonists, aminoglutethimide). Special types of pituitary adenomas can be treated with drugs which suppress hormone production and proliferation. Dopamine agonists and somatostatin reduce the tumor size of varying proportions of GH secreting adenomas in acromegaly. Ultrastructurally, a decrease of cytoplasmic and nuclear volume and an increase of lysosomes are found. Bromocriptine and other dopamine agonists are established in the treatment of prolactin secreting adenomas. They induce a shrinkage in many cases. Ultrastructurally, a reduction of cellular and nuclear size, an increase in number of secretory granules and of lysosomes, and a reduction of rough endoplasmic reticulum can be demonstrated.

Electron microscopical morphometry of well-differentiated and undifferentiated ACTH secreting adenomas in Cushing's disease and Nelson's syndrome

Adrenocorticotrophic hormone (ACTH)-secreting adenomas of patients with Cushing's disease (undifferentiated and well-differentiated ACTH-cell adenomas) were studied ultrastructurally and analysed morphometrically by a computer-supported quantitative image-analysing system. They were compared with identically prepared ACTH tumours (undifferentiated and well-differentiated ACTH-cell adenomas) of pituitaries from bilateral adrenalectomised patients with Nelson's syndrome. The aim of our study was to look for significant differences in ultrastructure and to evaluate these findings statistically regarding adenoma types and clinical syndromes. Clinical syndromes aside, more secretory granules and larger-sized prosecretory granules were measured in the well-differentiated ACTH-cell adenomas. The undifferentiated adenomas showed a greater content of nucleoli and prosecretory granules. Within the adenoma types, comparison of well-differentiated ACTH-cell adenomas showed that the clinical group of Cushing's disease contained larger areas of cytofilaments, whereas the clinical group of Nelson's syndrome had a larger tumour size and more lysosomes. Comparing the undifferentiated adenomas of both clinical groups the adenomas in Cushing's disease contained larger nuclei and more lysosomes, whereas the adenomas in Nelson's syndrome were larger in tumour size and contained larger prosecretory granules. Comparison of well-differentiated and undifferentiated adenomas in Cushing's disease showed more secretory granules and bigger prosecretory granules in well-differentiated adenomas whereas in undifferentiated adenomas the total area of the nuclei is larger, the nucleoli increase in number and size and the lysosomes are more frequent. Comparison of well-differentiated and undifferentiated adenomas in Nelson's syndrome demonstrated more lysosomes in well-differentiated adenomas and a larger total area of the nuclei in undifferentiated adenomas. The differences between the well-differentiated adenomas (mainly more secretory granules and larger prosecretory granules) and undifferentiated adenomas (mainly more and larger nuclei and nucleoli and more prosecretory granules) prove the clear separability between the adenoma types, not demonstrated in the literature up to now. The significant differences between adenomas in Cushing's disease (mainly more cytofilaments) and Nelson's syndrome (mainly more ribosomes and larger prosecretory granules) may be interpreted as different cell reactions due to the hypercortisolism present in Cushing's disease and lacking in Nelson's syndrome following adrenalectomy. Despite the fact that both clinical syndromes are based on the same adenoma types, indistinguishable by light microscopy, significant morphometrical findings in ultrastructure allow a clear discrimination of both clinical types.

Transnasal microsurgery of Cushing's disease 1990. Overview including personal experiences with 256 patients

The current concepts of differential diagnosis and therapy of Cushing's disease are reviewed. Our own results in a recent series of 103 patients are compared with patients treated by transsphenoidal microsurgery until 1986. In 97% as compared to 91% of prior series a discrete adenoma was found and selective adenomectomy led to remission in about 90%. The endocrine tests alone proved to be highly reliable to discriminate pituitary-dependent Cushing's disease from other forms of Cushing's syndrome. All our 3 patients without pituitary adenoma had some atypical endocrine tests. From these findings and results of other published series invasive investigations as inferior petrosal venous sampling may be reserved for equivocal cases. Magnetic resonance imaging now reveals two thirds of the micro-adenomas and provides the surgeon with excellent anatomical pictures. Rapid intraoperative measurement of peripituitary venous ACTH gradients may help to identify occult adenomas. In spite of different modes of therapy as pharmacological suppression of the adrenals and more sophisticated forms of radiotherapy, transsphenoidal microadenomectomy in experienced hands remains the most effective and the only immediately definite treatment of Cushing's disease.

Surgical pathology of the pituitary in Cushing's disease

The frequency and the significance of the 3 main features of pituitary in Cushing's disease (ACTH secreting adenomas, ACTH cell hyperplasia, and Crooke's cells) are reported and discussed. In our most recent surgical series (1989-1990) the rate of demonstration of adenoma increased up to 96%. The frequency of paraadenomatous ACTH cell hyperplasia depends on the amount of resected tumor-free tissue. The significance of such peritumorous hyperplasia seems to be low. Crooke's cells as suppressed and transformed ACTH cells were present in each case and are a reliable indicator of a hypercortisolism.

Immunoreactive luteinizing hormone in functioning corticotroph adenomas of the pituitary. Immunohistochemical and tissue culture studies of two cases

Two pituitary adenomas removed from a 37-year-old woman and a 26-year-old woman with typical Cushing's disease were studied by light and electron microscopy, immunohistochemistry and radioimmunoassay of tissue culture media. Both patients had high plasma levels of cortisol and normal levels of luteinizing hormone (LH). Both tumours were monomorphous, composed of densely granulated corticotrophs; the tumour cells contained periodic acid-Schiff positivity, were arranged in a sinusoidal pattern and, ultrastructurally, contained well-developed cytoplasmic organelles. By immunohistochemistry the majority of tumour cells contained immunoreactive adrenocorticotropin (ACTH); approximately 10% of the tumour cell population contained LH immunoreactivity. The LH-positive cells tended to form clusters scattered widely throughout the tumour tissues. LH immunoreactivity was demonstrated in some ACTH-immunoreactive cells on serial sections. Large amounts of immunoreactive ACTH and smaller quantities of LH, follicle stimulating hormone and alpha-subunit were released into the culture media and release of the glycoprotein hormones responded in parallel to corticotropin releasing hormone stimulation or inhibition by cortisol. These findings indicate that LH can be simultaneously produced and released by ACTH-producing tumour cells of otherwise typical functioning corticotroph adenomas. The capacity for LH production may be acquired during neoplastic proliferation. This is the first detailed report of concurrent production of LH by pituitary corticotroph adenomas.

Immunohistological studies on clinically silent pituitary adenomas

Clinically inactive adenomas represent 30.7% of all pituitary tumors in our surgical collection of 616 cases. Ninety-six tumors were studied immunohistologically with many antibodies for their hormone content. Morphological classification of these adenomas reveals oncocytic adenomas in 42 cases (44%), small cell chromophobe adenomas in 33 (34%), large cell chromophobe adenomas in 14 cases (15%), undifferentiated mucoid cell adenomas in 4 cases (4%) and undifferentiated acidophil adenomas in 3 cases (3%). Immunohistological studies performed with the six pituitary hormones GH, prolactin, ACTH, TSH, LH and FSH and additionally with α-subunit demonstrated nearly all possible combinations of hormones in adenoma cells. The most frequently occurring (29%) was LH (in 3% of adenomas alone); α-subunit followed in frequency (24%), with FSH present in 21%. Combinations of 2 hormones were detected in 16%, of 3 in 13% and of more than 3 hormones in 2%. All 6 hormones and α-subunit were negative in 48% of adenomas. It must be concluded 1) that many clinically silent adenomas are LH- or FSH- or α:-subunit-positive and therefore probably originate from gonadotropic cells, and 2) that clinically silent adenomas of acidophil cell type or mucoid cell type are rare. Although many of these adenomas apparently do not secrete the hormone which they immunohistologically contain, determining the plasma levels of the gonadotropins, and especially the α-subunit in clinical studies, may obtain a suitable and helpful clinical marker in the diagnosis of "endocrine inactive" adenomas, and especially of their recurrences.