Typing of inflammatory lesions of the pituitary.

Inflammatory pituitary lesions account for 1.8% of all specimens from the German Pituitary Tumor Registry. They occure in 0.5% of the autoptical specimens and in 2.2% of the surgical cases. Women are significantly more often affected than men and are often younger when first diagnosed. In general, primary and secondary inflammation can be distinguished, with secondary types occurring more frequently (75.1%) than idiopathic inflammatory lesions (15.4%). In primary inflammation, the lymphocytic type is more common (88.5%) than the granulomatous type of hypophysitis (11.5%). The most common causes of secondary inflammation are Rathke's cleft cysts (48.6%), followed by tumors (17.4%) such as the craniopharyngioma (9.1%), adenoma (5.5%) or germinoma (2.0%). More causes are tumor-like lesions (7.1%) such as xanthogranuloma (3.5%) or Langerhans histiocytosis (3.5%), abscesses (5.5%), generalized infections (5.1%), spreaded inflammations (4.7%) and previous surgeries (4.0%). In 1.6% of all specimens the reason for the inflammation remains unclear. The described classification of hypophysitis is important for specific treatment planning after surgery.

Acquired temozolomide resistance in human glioblastoma cell line U251 is caused by mismatch repair deficiency and can be overcome by lomustine.

PURPOSE: Glioblastoma multiforme (GBM) is the most common malignant primary brain tumor in adults. While the alkylating agent temozolomide (TMZ) has prolonged overall survival, resistance evolution represents an important clinical problem. Therefore, we studied the effectiveness of radiotherapy and CCNU in an in vitro model of acquired TMZ resistance. METHODS: We studied the MGMT-methylated GBM cell line U251 and its in vitro derived TMZ-resistant subline, U251/TMZ-R. Cytotoxicity of TMZ, CCNU, and radiation was tested. Both cell lines were analyzed for MGMT promotor status and expression of mismatch repair genes (MMR). The influence of MMR inhibition by cadmium chloride (CdCl2) on the effects of both drugs was evaluated. RESULTS: During the resistance evolution process in vitro, U251/TMZ-R developed MMR deficiency, but MGMT status did not change. U251/TMZ-R cells were more resistant to TMZ than parental U251 cells (cell viability: 92.0% in U251/TMZ-R/69.2% in U251; p = 0.032) yet more sensitive to CCNU (56.4%/80.8%; p = 0.023). The effectiveness of radiotherapy was not reduced in the TMZ-resistant cell line. Combination of CCNU and TMZ showed promising results for both cell lines and overcame resistance. CdCl2-induced MMR deficiency increased cytotoxicity of CCNU. CONCLUSION: Our results confirm MMR deficiency as a crucial process for resistance evolution to TMZ. MMR-deficient TMZ-resistant GBM cells were particularly sensitive to CCNU and to combined CCNU/TMZ. Effectiveness of radiotherapy was preserved in TMZ-resistant cells. Consequently, CCNU might be preferentially considered as a treatment option for recurrent MGMT-methylated GBM and may even be suitable for prevention of resistance evolution in primary treatment.

Novel technique for high-precision stereotactic irradiation of mouse brains.

BACKGROUND AND PURPOSE: Small animal irradiation systems were developed for preclinical evaluation of tumor therapy closely resembling the clinical situation. Mostly only clinical LINACs are available, so protocols for small animal partial body irradiation using a conventional clinical system are essential. This study defines a protocol for conformal brain tumor irradiations in mice. MATERIALS AND METHODS: CT and MRI images were used to demarcate the target volume and organs at risk. Three 6 MV photon beams were planned for a total dose of 10 fractions of 1.8 Gy. The mouse position in a dedicated applicator was verified by an X­ray patient positioning system before each irradiation. Dosimetric verifications (using ionization chambers and films) were performed. Irradiation-induced DNA damage was analyzed to verify the treatment effects on the cellular level. RESULTS: The defined treatment protocol and the applied fractionation scheme were feasible. The in-house developed applicator was suitable for individual positioning at submillimeter accuracy of anesthetized mice during irradiation, altogether performed in less than 10 min. All mice tolerated the treatment well. Measured dose values perfectly matched the nominal values from treatment planning. Cellular response was restricted to the target volume. CONCLUSION: Clinical LINAC-based irradiations of mice offer the potential to treat orthotopic tumors conformably. Especially with respect to lateral penumbra, dedicated small animal irradiation systems exceed the clinical LINAC solution.

Clinical Impact of the Current WHO Classification of Pituitary Adenomas.

WHO classifications should be used for comparing the results from different groups of pathologist and clinicians by standardized histopathological methods. Our present report describes the important parameters of pituitary adenoma pathology as demand of the WHO classification for correlation to endocrine data and prognosis. The combination of HE stain based structures with immunostainings for pituitary hormones allows subclassification of adenomas as the best method not only for correlations to clinical hyperfunctions but also for statements to the sensitivity of drug therapies (somatostatin analogs, dopamine agonists). GH-, PRL- and ACTH-secreting pituitary adenomas are further classified based on the size and number of their secretory granules by electron microscopy, or as is mostly the case nowadays by cytokeratin staining pattern, into densely and sparsely granulated. Granulation pattern may be considered for the prediction of treatment response in patients with GH-secreting adenomas, since the sparsely granulated subtype was shown to be less responsive to somatostatin analog treatment. For prognosis, it is important to identify aggressive adenomas by measurements of the Ki-67 index, of the number of mitoses, and of nuclear expression of p53. Among the criteria for atypical adenomas, high Ki-67 labeling index and invasive character are the most important adverse prognostic factors. Promising molecular markers have been identified that might supplement the currently used proliferation parameters. For defining atypical adenomas in a future histopathological classification system, we propose to provide the proliferative potential and the invasive character separately.

Emerging Histopathological and Genetic Parameters of Pituitary Adenomas: Clinical Impact and Recommendation for Future WHO Classification.

The review assesses immunohistochemical findings of somatostatin receptors and of metalloproteinases in different pituitary adenoma types and the significance of molecular genetic data. Current evidence does not support routine immunohistochemical assessment of somatostatin or dopamine receptor subtype expression on hormone-secreting or nonfunctioning pituitary adenomas. Further prospective studies are needed to define its role for clinical decision making. Until then we suggest to restrict membrane receptor profiling to individual cases or for study purposes. The problems of adenoma expansion and invasion are discussed. Despite partially contradictory publications, proteases clearly play a major role in permission of infiltrative growth of pituitary adenomas. Therefore, detection of at least MMP-2, MMP-9, TIMP-2, and uPA seems to be justified. Molecular characterization is important for familial adenomas, adenomas in MEN, Carney complex, and McCune-Albright syndrome and can gain insight into pathogenesis of sporadic adenomas.

Expression pattern of neuronal intermediate filament α-internexin in anterior pituitary gland and related tumors.

PURPOSE: α-Internexin (INA) is a class IV neuronal intermediate filament protein that maintains the morphogenesis of neurons. It is expressed in developing neuroblasts and represents the major component of the cytoskeleton in cerebellar granule cells of adult central nervous system tissue. Data concerning INA expression in the human frontal pituitary lobe and related adenomas (PA) is missing. METHODS: Using immunohistochemistry we examined the distribution pattern of INA in a large cohort of 152 PA, 11 atypical PA, 4 pituitary carcinomas and 20 normal pituitaries (overall n = 187). Quantity of INA protein expression was semi-quantitatively evaluated and grouped into five categories (0 = 0%; 1 = >0-5%; 2 = >5-35%; 3 = >35-80%; 4 = >80% of cells). RESULTS: Cellular staining intensity of INA appeared significantly higher in gonadotropinomas (Go, n = 62), null cell adenomas (NC, n = 7) and thyrotropinomas (TSHomas, n = 7) compared to the other tumor subtypes (p ≤ 0.001). Furthermore, Go and NC showed a peculiar pseudorosette-like staining pattern surrounding blood vessels in 85.5% (59/69) of cases. Interestingly, areas exhibiting homogenous INA staining were often associated with oncocytic cell changes and decreased immunohistochemically detectable hormone expression. Only 8.5% (8/94) of other PA showed a comparable INA distribution (p ≤ 0.001). CONCLUSION: Go, NC as well as TSHomas exhibit high levels of intracellular INA protein indicating neuronal transdifferentiation. A possible impact on pathogenesis and endocrine activity needs further investigation.

No effect of the PPAR-gamma agonist rosiglitazone on ACTH or cortisol secretion in Nelson's syndrome and Cushing's disease in vitro and in vivo.

OBJECTIVE: Surgical tumor resection remains the primary treatment strategy in ACTH-secreting pituitary adenomas, i.e. Cushing's disease (CD) and Nelson's syndrome (NS). However, an effective long-term pharmacological regime is not available in patients with persistent ACTH-hypersecretion. The nuclear receptor peroxisome proliferator-activated receptor gamma (PPAR-gamma) is abundantly expressed in most pituitary adenomas. First encouraging data reported that the PPAR-gamma ligand rosiglitazone antagonizes ACTH hypersecretion and exerts also antiproliferative effects in pituitary cell lines. Herein, we studied the potential therapeutical effects of rosiglitazone in patients with ACTH-secreting pituitary adenomas in vitro and in vivo. MATERIALS AND METHODS: Seven patients with persistent ACTH-hypersecretion (3 with NS, 4 with persistent CD) were treated 5 months with rosiglitazone (4 - 16 mg/day). In vitro assays were performed in primary cell cultures obtained from eight additional patients with ACTH-secreting pituitary adenomas applying 80 microM rosiglitazone repeatedly over a time period of 14 days. RESULTS: Our long-term clinical trial with the PPAR-gamma activator rosiglitazone showed no amelioration of clinical symptoms nor an inhibiting effect on ACTH-secretion in vivo. In vitro, rosiglitazone treatment led to a statistically significant decrease of ACTH levels in 2 out of 8 primary cell cultures after 14 days compared to untreated controls. CONCLUSION: In contrast to the initially promising laboratory data gathered in pituitary cell line experiments and nude mice models, our experimental data obtained in primary human ACTH-expressing pituitary adenoma cell cultures as well as our clinical experience with a long-term rosiglitazone trial in approved antidiabetic doses support the recently reported disappointing reports on acute or short-term medical treatment of ACTH-hypersecretion with PPAR-gamma activators.

Evidence for a progenitor cell population in the human pituitary.

The ability to isolate and propagate adult stem/progenitor cells from the human brain opens novel avenues for cell replacement therapy. This will also apply to the pituitary gland, i.e., following tumor induced endocrine deficiency. Herein, we examine autopsy derived pituitaries to unravel a putative stem/progenitor cell population in humans. In tissue sections of the anterior lobe nestin immunoreactive cells co-expressing smooth muscle actin (SMA) were identified in the perivascular space, indicating a pericytic differentiation. Under clonal conditions, this particular cell population generated primary and secondary cell aggregates (spheres). Pituitary cell cultures maintained a stable cell cycle length with a doubling time of 10 days for over eight months. Forskolin treatment induced a prolactin-expressing phenotype in the majority of cell progenies as well as few betaIII-tubulin (Tuj1) expressing cells of putative neuronal lineage. The presence of sphere-forming, nestin-immunoreactive cells and their ability to generate differentiated cell lineages indicates the existence of a progenitor cell population persisting in the adult human pituitary. Further studies are needed to characterize this cell population in more detail and to clarify their potential to initiate neoplastic transformation for example in the cellular pathogenesis of pituitary adenoma.

Operative treatment of prolactinomas: indications and results in a current consecutive series of 212 patients.

OBJECTIVE: Medical therapy with dopamine agonists (DA) is the primary treatment of choice in most patients with prolactinomas. 'Classical' surgical indications are intolerance or lack of efficiency of DA therapy. Focusing on a possible shift of recent indications, we retrospectively analyzed our results of surgical treatment in prolactinomas. PATIENTS AND METHODS: Between 1990 and 2005, we have operated on 212 consecutive patients with prolactinomas. Surgical indications were divided into 'classical' indications and 'modern' indications defined as cystic prolactinomas or patients with microprolactinomas who individually decided on a primary surgical treatment. RESULTS: Initial overall remission was accomplished in 53.2% including giant prolactinomas. However, in microadenomas, the remission rate was significantly higher with 91.3%. Overall remission at the latest follow-up was 42.7%, but 72.5% in intrasellar tumors, 80% in cystic prolactinomas, and 84.8% in microprolactinomas. The overall recurrence rate was 18.7%. Relapse of hyperprolactinemia in microprolactinomas was 7.1%. In our series, continually less patients were surgically treated for 'classical' indications. By contrast, the number of patients who individually decided on a primary surgical therapy has increased considerably. CONCLUSION: Remission rates after surgical treatment of prolactinomas remain excellent, particularly in microadenoma and intrasellar macroadenomas, whereas morbidity of transsphenoidal surgery is low in the hands of experienced pituitary surgeons. Our remission rates not only confirm the already interdisciplinarily accepted surgical indications, but also emphasize the value of primary transsphenoidal surgery as a discussion-worthy alternative to dopaminergic therapy in young patients with microprolactinomas or cystic tumors.

Atypical type II silent corticotrophic adenoma developing into Cushing's disease upon second recurrence.

Herein, we report the case of a 73-year old male patient who presented with two recurrences of a pituitary adenoma within a period of 15 years. The first tumor resection 15 years ago revealed a non-functioning pituitary macroadenoma. 11 years later, the first recurrence of the tumor was reoperated. Throughout the early course of the disease, he suffered from secondary adrenal insufficiency and required replacement therapy with hydrocortisone. Currently, he presented with the second recurrence and clinical examination revealed signs of Cushing's disease. This was clearly confirmed by endocrinological evaluation. A retrospective analysis of all histological and immunohistochemical slides rendered an adenoma exhibiting chromophobia, ACTH-positivity and features of atypia such as elevated p53 and Ki67 expression as well as nuclear polymorphism. According to the revised WHO classification it was classified as atypical type II silent corticotroph adenoma at the time of the first and second surgery. The specimen removed during the recent surgery displayed the same histological features and was classified as corticotroph adenoma. The combination of an atypical type II adenoma and the switch in the hormone status to an endocrinologically active adenoma makes this case exceedingly rare.

Alveolar rhabdomyosarcoma of the clivus with intrasellar expansion: Case report.

Rhabdomyosarcomas are common tumors of the head and neck region in children. However, a primarily intracranial localization of this tumor entity is rare. We report on a 3-year-old boy presenting with double vision due to left VI (th) nerve palsy. No other neurological deficits were recognized by clinical inspection. MRI scans visualized an enhancing mass lesion in the upper clivus compressing the cavernous sinus and the pituitary gland. Transsphenoidal biopsy was performed and histopathological examination as well as molecular diagnostics confirmed the diagnosis of an alveolar rhabdomyosarcoma (ARMS). Staging identified a metastatic lesion in the fourth thoracic vertebra resulting in the diagnosis of stage IV disease. Treatment modality included stereotactic radio- and chemotherapy.

Intradural-extramedullary cavernous hemangioma of the left motor root C7--case report and update of the literature.

OBJECTIVE: Intradural-extramedullary cavernomas of the spine are rare lesions with only 21 published cases to date. Due to their rareness and special characteristics diagnosis often is difficult. We report on an additional case of an intradural-extramedullary cavernoma of the spine. PATIENT: A 56-year-old male presented with left shoulder pain and acute onset of pain affecting the whole spinal column two weeks prior to admission. There were no motor deficits, but a hypesthesia corresponding to the right distal C8-dermatome. MRI revealed an intradural-extramedullary, expansive lesion at the level of C6 with a hyperintense appearance in both T (1)- and T (2)-weighted images. Neither a hemosiderin rim nor contrast enhancement was visible. RESULTS: During surgery a hematoma and a reddish, berry-like tumor adherent to the left motor root C7 were removed. There were no new neurological deficits, and shoulder and back pain resolved within a few weeks after surgery. Histopathologically a cavernous hemangioma was diagnosed. CONCLUSIONS: The patient's symptoms were caused both by direct nerve compression and by spinal hemorrhage, most likely spinal SAH. As there was no characteristic hemosiderin rim and due to the hyperintense appearance in T (1)- and T (2)-weighted MR scans, a radiological diagnosis of hemorrhage and classification of the lesion was difficult. Despite their rareness, in patients with signs of spontaneous, spinal SAH and/or nerve compression syndromes cavernous hemangiomas have to be considered as a potential cause.

Immunopathology of primary hypophysitis: implications for pathogenesis.

The etiology of primary hypophysitis is still not fully elucidated. Histologically, primary hypophysitis includes three different main subtypes: lymphocytic (LYH), granulomatous (GRH), and xanthomatous (XH) hypophysitis. Clinical and laboratory findings suggest an autoimmune basis in primary hypophysitis. Controversy still exists about the composition of the inflammatory infiltrate and the relevant immunopathogenic effector mechanisms. Therefore, 21 cases of primary hypophysitis of different subtypes were analyzed with respect to the expression of lymphocyte and macrophage antigens as well as MHC class I and II molecules of the inflammatory infiltrate and the resident pituitary acinar cells. Lymphocyte infiltration in LYH (n = 15), but also in GRH (n = 4) and XH (n = 2), mainly consisted of T cells, while B cells were rare. Independent from the histopathologic subtype, T cell subsets showed equal ratios of CD4+ to CD8+ T cells. Highest numbers of activated CD8+ T cells were observed in LYH presenting during pregnancy, surrounding or even infiltrating preserved pituitary acinar cells. Moreover, an increased rate of activated CD8+ T cells correlated with a shorter duration of clinical symptoms. In LYH, aberrant expression of MHC class II antigens as well as overexpression of MHC class I molecules on pituitary cells were observed. Independent of the histologic subtype, macrophages mostly expressed markers of chronic activation and showed MHC class II positivity. LYH, GRH, and XH, although heterogeneous in their histologic appearance and in age distribution, exhibit a similar if not identical immunohistologic profile. It is highly likely that direct T cell-mediated cytotoxicity through CD8+ T cells, with the initial help of CD4+ T cells, is pivotal in the pathogenesis of primary hypophysitis, implicating a target autoantigen expressed by pituitary cells.

Differentiation of radiation necrosis from tumor progression using proton magnetic resonance spectroscopy.

We report on a young woman who was treated by stereotactic radiotherapy for recurrence of an initially resected low-grade astrocytoma. MRI follow-up examination 7 months after radiotherapy showed a gadolinium-DTPA-enhancing mass lesion indicative of high-grade tumor progression. This assumption was also supported by positron emission tomography with [2-18F]fluoro-2-deoxy-D-glucose (FDG-PET). In contrast, proton MR spectroscopy (1H-MRS) indicated radiation necrosis, which was confirmed histopathologically in surgical specimens. Subsequent follow-up examinations up to 19 months after surgery showed no evidence of tumor recurrence.

Expression of the neurotrophin receptor p75NTR in medulloblastomas is correlated with distinct histological and clinical features: evidence for a medulloblastoma subtype derived from the external granule cell layer.

Medulloblastomas (MBs) are primitive neuroectodermal tumors (PNET) of the cerebellum. They represent the most frequent malignant pediatric brain tumors, but their origin still remains unresolved and controversial. MB cells correspond to different stages of neural development and differentiation as illustrated by their expression of neuronal and glial markers. In the present study, we examined the expression pattern of the common low-affinity neurotrophin receptor p75NTR in a series of 167 MBs by immunohistochemistry. While p75NTR was present in only 17% of classic MBs (CMB), we found expression of p75NTR in all desmoplastic (nodular) MBs (DMB) examined, and in 71% of those MBs with a significant desmoplastic component. Furthermore, both desmoplastic histology and p75NTR expression were present preferentially in those tumors of adolescents and adults that are frequently located laterally in the cerebellar hemispheres. In DMBs, p75NTR was expressed predominantly in the proliferative, reticulin-rich areas, which may show coexpression of GFAP. In the pale islands of DMB, p75NTR was expressed only weakly or was absent. The expression pattern showed an inverse relation to that of the synaptic vesicle protein synaptophysin that was predominant in p75NTR negative classic MBs. Since the neurotrophin receptor p75NTR is expressed in cells of the external granule cell layer (EGL) of the fetal cerebellum, our findings suggest that progenitor cells of the EGL are the cellular origin of a distinct subset of MB, namely the desmoplastic variant and MBs with a significant desmoplastic component.