Malignant prolactinoma with extracranial metastases: a report of three cases

Refractory lactotroph adenomas

A small subset of lactotroph adenomas is resistant to dopamine agonists (DA) and can also demonstrate aggressive or even malignant behavior. The implicated mechanisms are not clearly defined. Management can be challenging and requires a multidisciplinary approach. In DA resistant prolactinomas, switching to another DA could be the first option to consider. Further strategies include surgery and radiotherapy used alone or in combination. In cases of aggressive or malignant prolactinomas, temozolomide could be offered. Immune checkpoint inhibitors have been also recently proposed as an alternative approach. The place of other treatments (e.g., metformin, selective estrogen modulators, somatostatin analogues, tyrosine kinase inhibitors, inhibitors of mammalian target of rapamycin and peptide radio-receptor therapy) remains to be carefully assessed.

Approach to the Treatment of a Patient with an Aggressive Pituitary Tumor

A small subset of pituitary adenomas grows despite maximal treatment with standard therapies; namely, surgery and radiotherapy. These aggressive tumors demonstrate 2 patterns of growth: they may be locally aggressive or metastasize distantly, either hematogenously or through the spinal fluid. Further surgery and radiotherapy may be helpful for palliation of symptoms, but they are rarely definitive in the management of these malignant tumors. The only chemotherapy with established activity in the treatment of pituitary tumors is the alkylating agent temozolomide. At most, 50% of patients exhibit an objective response to temozolomide and the median time to progression is short; thus, there remains a significant unmet need for effective treatments within this patient population. Several targeted agents have reported activity in this tumor type-including small molecule inhibitors, checkpoint inhibitors, and other biologics-but remain investigational at this time.

Targeted systemic and peptide radio-ligand therapy for aggressive pituitary tumors and carcinomas

Aggressive pituitary tumors comprise a rare but challenging subset of pituitary tumors. A major issue currently is the absence of a holistic definition that reliably identifies these tumors in a prospective manner. Although comprehensive evaluation of patient gender, age, local invasiveness, treatment responses, radiological and histopathological features may be informative to assess the potential for aggressiveness, a definitive diagnosis of this entity cannot be confidently made until disease progression is actually observed despite standard medical and surgical therapy. Failure to diagnose these aggressive pituitary tumors early may impede initiation of suitable intensive stepwise multimodal treatments, and lessen their ultimate therapeutic success. Even though current therapeutic options for aggressive pituitary tumors are suboptimal in many cases, large-scale randomized prospective clinic trials are impractical and will likely never be conducted due to the rarity of this disease entity. Therefore, the majority of novel therapies in this subset of tumors derive from case reports or small case series, which greatly reduces their validity to make strong recommendations. This chapter, as part of this series on aggressive pituitary tumors, focuses on the role of systemic targeted medical and peptide radio-receptor therapy in treatment of aggressive pituitary tumors and carcinomas, and discusses future directions in these fields.

Dopamine agonist resistant prolactinomas: any alternative medical treatment?

Consensus guidelines recommend dopamine agonists (DAs) as the mainstay treatment for prolactinomas. In most patients, DAs achieve tumor shrinkage and normoprolactinemia at well tolerated doses. However, primary or, less often, secondary resistance to DAs may be also encountered representing challenging clinical scenarios. This is particularly true for aggressive prolactinomas in which surgery and radiotherapy may not achieve tumor control. In these cases, alternative medical treatments have been considered but data on their efficacy should be interpreted within the constraints of publication bias and of lack of relevant clinical trials. The limited reports on somatostatin analogues have shown conflicting results, but cases with optimal outcomes have been documented. Data on estrogen modulators and metformin are scarce and their usefulness remains to be evaluated. In many aggressive lactotroph tumors, temozolomide has demonstrated optimal outcomes, whereas for other cytotoxic agents, tyrosine kinase inhibitors and for inhibitors of mammalian target of rapamycin (mTOR), higher quality evidence is needed. Finally, promising preliminary results from in vitro and animal reports need to be further assessed and, if appropriate, translated in human studies.

Pituitary carcinomas: review of the current literature and report of atypical case

Introduction: Pituitary carcinomas are poorly understood, rare entities. They are distinguished from adenomas not by histopathological features but rather by the presence of metastases.Objective: We discuss the diagnosis, mechanism of dissemination and pathogenesis based on a review of the literature and illustrated by a singular case.Case Report: A 59-year-old male presented with a dural-based posterior fossa lesion. He had been diagnosed with a pituitary chromophobe adenoma 43 years earlier that was treated at the time with surgery and radiation therapy. A presumptive diagnosis of a radiation-induced meningioma was made and surgery was recommended. At surgery the tumour resembled a pituitary adenoma. Histopathology, laboratory findings, and the patient's medical history confirmed the final diagnosis of a prolactin-secreting pituitary carcinoma. To our knowledge, this is the longest reported interval between the pituitary adenoma and metastatic lesion diagnosis (43 years).Conclusion: Management should be tailored to individual patient and may include a combination of treatments (surgery, radiation therapy, chemotherapy, and hormone-targeted therapy). Functionally active tumours may be monitored with hormone levels as tumour markers.

Aggressive and Malignant Prolactinomas

Prolactin-secreting tumors (prolactinomas) represent the most common pituitary tumor type, accounting for 47-66% of functional pituitary tumors. Prolactinomas are usually benign and controllable tumors as they express abundant levels of dopamine type 2 receptor (D2), and can be treated with dopaminergic drugs, effectively reducing prolactin levels and tumor volume. However, a proportion of prolactinomas exhibit aggressive features (including invasiveness, relevant growth despite adequate dopamine agonist treatment, and recurrence potential) and few may exhibit metastasizing potential (carcinomas). In this context, the clinical, pathological, and molecular definitions of malignant and aggressive prolactinomas remain to be clearly defined, as primary prolactin-secreting carcinomas are similar to aggressive adenomas until the presence of metastases is detected. Indeed, standard molecular and histological analyses do not reflect differences between carcinomas and adenomas at a first glance and have limitations in prediction of the aggressive progression of prolactinomas, wherein the causes underlying the aggressive behavior remain unknown. Herein we present a comprehensive, multidisciplinary review of the most relevant epidemiological, clinical, pathological, genetic, biochemical, and molecular aspects of aggressive and malignant prolactinomas.

Biomarkers of pituitary carcinomas

Pituitary carcinoma is a rare tumor originating from adenohypophyseal cells. Currently, diverse pathogenetic mechanisms, i.e. de novo versus malignant transformation from pituitary adenoma, remain obscure and require further investigation. During the last two decades, scientific research added new horizons not only in regards to general tumor concepts but also in next generation biomarker armamentarium that sheds light on alternate pathways in carcinogenesis. Areas covered: In this review, the impact of apoptotic and proliferative markers, angiogenesis, telomerase activity, H-ras, HIF-1, HER-2/neu, Rb gene, and microRNAs in pathogenetic mechanisms of pituitary carcinomas were revised. Expert commentary: It is becoming increasingly important for the need of standardization of new biomarkers but also for better comprehension of the diverse pathways in tumorigenesis. This can only be accomplished by tapping into the continuously expanding spectrum of new biomarkers.

Is there a role for early chemotherapy in the management of pituitary adenomas?

Pituitary adenomas are benign intracranial neoplasms that are frequently well-controlled with standard treatments that include surgical resection, radiotherapy, and agents that modulate hormonal excess. Unfortunately, a subset of patients remains uncontrolled or develops complications from these interventions. For these patients, chemotherapy is an additional treatment option that could improve outcomes. Temozolomide is an oral chemotherapy with a favorable side-effect profile that has shown activity against pituitary adenomas. Its non-overlapping toxicity and ability to induce rapid tumor regression renders it a potentially important adjunctive treatment. In patients with tumors that cannot be optimally addressed with standard treatments, there may be a role for early initiation of temozolomide.

Transsphenoidal surgery for malignant pituitary lesions: an analysis of inpatient complications

BACKGROUND

Fewer than 4% of pituitary tumors are malignant lesions. These tumors predominantly represent metastatic disease from elsewhere. This study evaluates inpatient complications, demographics, and hospitalization characteristics of patients who underwent transsphenoidal surgery (TSS) for malignant pituitary lesions.

METHODS

The Nationwide Inpatient Sample was evaluated for TSS patients from 1998 to 2010. Demographics, hospitalization characteristics, and complications were evaluated among patients with malignant lesions and compared to those with benign tumors.

RESULTS

There were 17,425 inpatient records, 1.0% of which involved malignant pituitary tumors. There was no difference in age between these cohorts (p = 0.378). Patients with malignant tumors had greater length of stay (6.7 days vs 4.5 days, p = 0.003) and higher trending charges ($55,371 vs $40,550 p = 0.091). The most common postoperative complications among patients with malignant lesions included diabetes insipidus (DI) (17.9%), fluid/electrolyte abnormalities (14.0%), neurological complications (5.6%), cerebrospinal fluid (CSF) rhinorrhea (2.2%), and iatrogenic pituitary disorders (2.2%). Patients with malignant lesions had a significantly greater rates of postoperative DI and fluid/electrolyte abnormalities (odds ratio = 2.0 and 1.7, respectively), whereas no statistical difference was noted in the rates of CSF rhinorrhea (p = 0.372).

CONCLUSION

In this analysis of inpatient hospitalizations for TSS patients, malignant pituitary disease was associated with a greater rate of postoperative DI and fluid/electrolyte abnormalities, but no differences in the rates of postoperative CSF rhinorrhea and other complications were found. Patients with malignant pituitary lesions undergoing TSS had significantly longer hospitalizations and higher trending charges than those with benign lesions. This analysis is, however, subject to the limitations of the database.

Treatment of pituitary carcinomas and atypical pituitary adenomas: a review

Atypical pituitary adenomas (APAs) are aggressive tumors, harboring a Ki-67 (MIB-1) staining index of 3% or more, and positive immunohistochemical staining for p53 protein, according to the World Health Organization (WHO) classification in 2004. Pituitary carcinomas (PC) usually develop from progressive APAs and predominantly consist of hormone-generating tumors, defined by the presence of disseminations in the cerebrospinal system or systemic metastases. Most of the cases with these malignant pituitary adenomas underwent surgeries, irradiations and adjuvant medical treatments, nevertheless, the therapies are mainly palliative. Recently, the efficacy of temozolomide (TMZ), an orally administered alkylating agent, has been reported as an alternative medical treatment. However, some recent studies have demonstrated a significant recurrence rate after effective response to TMZ. Further clinical and pathological researches of malignant pituitary adenomas will be required to improve the outcome of patients with these tumors.

Challenges and controversies in the treatment of prolactinomas

Recent studies have reported a higher prevalence of pituitary tumors than previously thought. Among these tumors, prolactinomas occur in up to 66% of cases. Since the mid-1980s, the widespread use of dopamine agonists has facilitated the management of the majority of prolactinomas, allowing biological and tumoral control in most cases. The less frequent cases of resistant prolactinomas remain challenging despite a multimodal therapy approach. The understanding of genetic alterations in familial and aggressive pituitary tumors provides new perspectives in the management of some prolactinomas. Genetic screening should be considered, particularly in familial cases but also in young patients with macroprolactinomas, as some mutations can predict potential aggressiveness.

Aggressive and malignant prolactin pituitary tumors: pathological diagnosis and patient management

According to the World Health Organization classification of pituitary tumors, only tumors with systemic metastasis must be considered as carcinomas. Invasive tumors with multiple recurrences are only classified as aggressive tumors or "atypical adenomas". To illustrate the problems encountered in the pathological diagnosis of pituitary carcinoma and in patient management, we present two male patients operated on for an aggressive prolactin pituitary adenoma with and without metastasis. In case 1, 5 surgeries, 3 irradiations, increased doses of dopamine agonists, and trials of temozolomide and carboplatine-VP16 failed to control tumor progression and the appearance of metastases which lead to death 16 years after onset. In case 2, based on the initial diagnosis of an aggressive-invasive adenoma that was resistant to dopamine agonists, gamma-Knife irradiation was initially performed on the intra-cavernous remnant. Eight years after onset, the remnant remained stabilized and the plasma PRL normalized under dopamine agonist. From these 2 cases alongside other cases found in the literature, we propose that the association of certain clinical signs (male sex, dopamine-resistant hyperprolactinemia), radiological signs (invasive macro or giant tumor on MRI) and histological signs (angiogenesis, Ki-67 > 3%, p53 positive, mitoses >2 per high power field, vascular invasion, up-regulation of genes related to invasion and proliferation, and allelic loss of chromosome 11) might suggest aggressiveness and be suspicious of malignancy before the appearance of metastasis. The early detection of an aggressive phenotype of a prolactin pituitary tumor should permit the earlier establishment of the optimum therapeutic strategy associating surgery and radiotherapy to delay or inhibit metastasis.

Clinical review: Pituitary carcinoma: difficult diagnosis and treatment

CONTEXT

Although pituitary tumors are common, pituitary carcinoma is very rare and is only diagnosed when pituitary tumor noncontiguous with the sellar region is demonstrated. Diagnosis is difficult, resulting in delays that may adversely effect outcome that is traditionally poor. Barriers to earlier diagnosis and management strategies for pituitary carcinoma are discussed.

EVIDENCE ACQUISITION

PubMed was employed to identify relevant studies, a review of the literature was conducted, and data were summarized and integrated from the author's perspective.

EVIDENCE SYNTHESIS

The available data highlight the difficulties in diagnosis and management and practical challenges in conducting clinical trials in this rare condition. They suggest that earlier diagnosis with aggressive multimodal therapy may be advantageous in some cases.

CONCLUSIONS

Although pituitary carcinoma remains difficult to diagnose and treat, recent developments have led to improved outcomes in selected cases. With broader use of molecular markers, efforts to modify current histopathological criteria for pituitary carcinoma diagnosis may now be possible. This would assist earlier diagnosis and, in combination with targeted therapies, potentially improve long-term survival.

Therapy of aggressive pituitary tumors

INTRODUCTION

Aggressive tumors of the pituitary gland are classically defined as pituitary tumors with a massive invasion of the surrounding anatomical structures and rapid growth. They are notoriously difficult to manage and are associated with poor prognosis because the therapeutic options are limited and the tumors are generally unresponsive to therapy.

AREAS COVERED

This review focuses on treatment options for aggressive pituitary tumors, including surgery, radiotherapy and medical treatment, as well as focusing on the promising therapeutic options for aggressive pituitary tumors, evaluating the literature of the last 15 years. With the exception of prolactinomas, surgery is the first-line option, but most aggressive pituitary tumors often require repeated surgery. Pharmacotherapies are useful when surgery is unlikely to improve symptoms, or as an adjunct therapy to surgery. In prolactinomas, dopamine agonists are the first-line treatment and normalize prolactin levels in most patients, even those with macroprolactinomas. Somatostatin analogs are effective agents for primary therapy, pre-operatively or post-operatively to control tumor re-expansion of pituitary adenomas. However, dopamine agonists and somatostatin analogs are not as effective as they are for the treatment of non-aggressive adenomas. When surgery and pharmacotherapy fail, radiotherapy is a useful third-line strategy. Conventional chemotherapy is poorly effective but recent case reports with the temozolomide, an alkylating agent, have provided better results in the short term.

EXPERT OPINION

Aggressive pituitary tumors are associated with poor prognosis as therapeutic options are limited. Moreover, they tend to recur quickly after initial treatment, are generally unresponsive to therapy, and are difficult to manage. To improve the overall response rate, the early application of current therapeutic approaches with the incorporation of new therapeutic developments is mandatory.

Advances in the treatment of prolactinomas

Prolactinomas account for approximately 40% of all pituitary adenomas and are an important cause of hypogonadism and infertility. The ultimate goal of therapy for prolactinomas is restoration or achievement of eugonadism through the normalization of hyperprolactinemia and control of tumor mass. Medical therapy with dopamine agonists is highly effective in the majority of cases and represents the mainstay of therapy. Recent data indicating successful withdrawal of these agents in a subset of patients challenge the previously held concept that medical therapy is a lifelong requirement. Complicated situations, such as those encountered in resistance to dopamine agonists, pregnancy, and giant or malignant prolactinomas, may require multimodal therapy involving surgery, radiotherapy, or both. Progress in elucidating the mechanisms underlying the pathogenesis of prolactinomas may enable future development of novel molecular therapies for treatment-resistant cases. This review provides a critical analysis of the efficacy and safety of the various modes of therapy available for the treatment of patients with prolactinomas with an emphasis on challenging situations, a discussion of the data regarding withdrawal of medical therapy, and a foreshadowing of novel approaches to therapy that may become available in the future.

Pathological changes after radiotherapy for primary pituitary carcinoma: a case report

Pituitary carcinomas are extremely rare. The definition, diagnosis, therapy, and prognosis are controversial. So far, to our knowledge, there has been no report regarding pathological changes after radiotherapy for primary pituitary carcinoma. We reported a single case of a presumed prolactin staining pituitary carcinoma. We defined carcinoma by premorbid intracranial dissemination of the tumor. There were no proven extracranial metastases. The tumor was silent on PET scanning. The patient received external beam radiotherapy alone as primary therapy. Post-irradiation histology revealed that necrotic tissue made up approximately more than half. Tumor had viable cells. Probably approximately three-fifth of tumor cells were without alteration and approximately two-fifth were with degeneration. We confirmed that necrosis but no apoptosis were coexistent in the cells post irradiation for pituitary carcinoma.

A case of prolactin-secreting pituitary carcinoma and its histological findings

Pituitary carcinomas are very rare. The diagnosis of pituitary carcinoma is defined by evidence of craniospinal and/or systemic metastasis, rather than by histological malignancies. We report a case of prolactin-secreting pituitary macroadenoma invading the cavernous sinuses at the time of initial treatment, which later metastasized to the cerebellum, medulla oblongata, and spinal axis. The patient survived approximately nine years following the initial diagnosis of a pituitary tumor and two years following the diagnosis of metastatic disease. Histological examination of the metastatic cerebellar tumor showed an adenoma with high cellularity and hyperchromasia, but no mitoses.

Pituitary carcinoma: a review of the literature

Pituitary carcinomas, defined as distant metastases of a pituitary neoplasm, are rare; fewer than 140 reports exist in the English literature. The initial presenting pituitary tumor is usually a secreting, invasive macroadenoma, with adrenocorticotropic hormone (ACTH)--and prolactin (PRL)--secreting tumors being the most common. The latency period between the diagnosis of a pituitary tumor and the diagnosis of a pituitary carcinoma is 9.5 years for ACTH-producing lesions and 4.7 years for PRL-secreting tumors. Survival after documentation of metastatic disease is poor; 66% of patients die within 1 year. Treatment options include additional surgery, radiotherapy, and chemotherapy, all of which are associated with poor results. Future studies will focus on identifying those invasive pituitary tumors most likely to metastasize and treating them aggressively before they progress to pituitary carcinomas.

Progression on metastatic neuroendocrine carcinoma from a recurrent prolactinoma: a case report

A 54 year old man was referred to the department of neurosurgery for frontal headache and vomiting. The patient was known in the department because of previous multiple surgery for a locally invasive pituitary prolactinoma (eight years, three years, and one year previously). The neurological examination revealed a frontal mass, which adhered to the dura, suggesting a meningioma. One year later, a left temporal metastasis was removed. Three months later, the patient died, with spinal metastases, of massive lung embolism. Histology revealed a progression of adenohypophyseal prolactinoma on neuroendocrine carcinoma, with an increase in proliferating indexes and modification of hormone production. This study documents a 10 year history of a rare prolactin producing pituitary carcinoma, which metastasised via liquoral flow.

Multiple intracranial recurrent tumors with hyperprolactinemia combined with a parasellar malignant fibrous histiocytoma long after transfrontal surgery and irradiation to a pituitary adenoma

We herein describe a 40-year-old woman with hyperprolactinemia, an empty sella and two extrasellar intracranial recurrent tumors which were revealed 23 years after the first transfrontal craniotomy and 18 years after the second transfrontal surgery and irradiation to a provable prolactin-producing pituitary macroadenoma. One recurrent tumor was in the right orbital apex causing right oculomotor nerve palsy, and the other tumor was in the right apex partispetrosae and foramen jugulare. Although her serum prolactin level decreased after the administration of bromocriptine mesilate, and the size of the two tumors remained unchanged, a malignant fibrous histiocytoma, which might have been induced by the irradiation 18 years before, grew rapidly in the right suprasellar-prepontine cistern to the right pedunculus cerebralis, leading to a poor prognosis. This case confirmed the importance of the life-lasting follow-up of pituitary adenomas treated with surgery and/or irradiation therapy. Not only ectopic recurrence of the primary tumor but also post-irradiation tumors may become apparent long after the removal of the primary tumor.

Pituitary carcinoma containing gonadotropins: treatment by radical excision and cytotoxic chemotherapy: case report

OBJECTIVE AND IMPORTANCE

Pituitary carcinomas are extremely rare. Cases reported in the medical literature in the 20th century included tumors that produced adrenocorticotropic hormone, prolactin, growth hormone, and/or thyrotropin.

CLINICAL PRESENTATION

Here we present a 22-year-old woman with a pituitary carcinoma that was immunohistochemically positive for luteinizing hormone and follicle-stimulating hormone at both the primary and metastatic sites. The patient exhibited elevated serum levels of alpha-subunit.

INTERVENTION

The patient had experienced failure of previous treatments, including standard surgery and radiotherapy, and presented to us for radical resection of the tumor, with exenteration of the involved cavernous sinus. She was pretreated with cytotoxic chemotherapy and continued to receive this therapy after surgery.

CONCLUSION

This is the only documented case of a gonadotropin-staining pituitary carcinoma for which hormone production was proven in both the primary and metastatic tumors. Many benign "nonsecreting" pituitary adenomas actually produce subclinical amounts of gonadotropins, and malignant nonfunctional pituitary neoplasms may do the same.

The pathology of pituitary tumors

The pathologist plays an important role in the distinction of pituitary adenomas from other tumors and tumor-like lesions of the sellar region, and in the accurate morphologic characterization of pitutiary adenomas. A clinicopathologic classification of pituitary adenomas is based on cell differentiation correlated with clinical evidence of hormone secretion; this classification emphasizes clinically relevant features that can offer guidance for patient management. The application of a rational approach to the immunohistochemical analysis of these lesions can be used to evaluate pathogenetic and prognostic markers and to predict responses to specific therapeutic modalities.

Malignant prolactinoma: case report and review of the literature

BACKGROUND

Malignant prolactinomas are rare events. To date, only 14 patients with metastases in- or outside the central nervous system have been reported.

CASE DESCRIPTION

We present a patient who developed a metastasis to the cauda equina, which is the first case documented with MRI. A giant prolactinoma in this 51-year-old man was partially removed by a transcranial approach. After radiotherapy and treatment with bromocriptine, the patient had a remission for 3 years. Thereafter, a sacral intraspinal tumor was diagnosed. Because of increasing prolactin levels not responding to bromocriptine and a radiologically suspected intrasellar tumor, we operated transsphenoidally first and found only fibrous tissue. We performed a sacral laminectomy and almost totally removed an intradural tumor. Histopathology and immunohistochemistry confirmed the diagnosis of a prolactinoma metastasis. The patient received radiotherapy and bromocriptine and has no evidence of recurrent tumor or metastases after a follow-up of 38 months, thus being the second reported patient with long-term remission of the disease.

DISCUSSION

We review the literature on this topic and try to establish common features of the course of this rare malignant disease and the efficacy of therapy in the cases reported hitherto.

Pituitary carcinoma: a clinicopathologic study of 15 cases

BACKGROUND

Pituitary carcinomas are rare adenohypophysial neoplasms, the definition, diagnosis, therapy, and prognosis of which are controversial.

METHODS

Pituitary carcinomas were defined as primary adenohypophysial neoplasms with documented craniospinal and/or systemic metastases. The authors report a clinicopathologic study of 15 examples examined by light microscopy, immunohistochemistry, and image analysis. Both proliferative activity and p53 tumor suppressor gene expression were studied.

RESULTS

The study group consisted of 15 patients, including 8 males and 7 females ranging in age from 34-71 years (mean, 56 years). Of these patients, seven had adrenocorticotropic hormone (ACTH)-producing tumors (four in the context of Nelson's syndrome), seven had prolactin-producing tumors, and one had a nonfunctioning tumor. No evidence of diabetes insipidus was seen in any case. Fourteen tumors were initially considered macroadenomas. Of the ten cases for whom tumor extent was known, all had invasive tumors. The interval from the initial diagnosis of adenoma to that of carcinoma ranged from 0.3 to 18.0 years (mean, 6.6 years; median, 5.0 years); the longest mean interval (15.3 years) occurred for patients with Nelson's syndrome. The latency was twice as long for ACTH-producing tumors as for prolactin (PRL) cell tumors (9.5 vs. 4.7 years). All carcinomas showed a greater tendency toward systemic metastasis than craniospinal metastasis; the rate of systemic metastasis was 71% for PRL cell tumors and 57% for ACTH-producing tumors. Thirteen percent of tumors showed both patterns of metastasis. Fully 50% of primary tumors and the majority of metastases showed nuclear pleomorphism and/or hyperchromasia. The mean mitotic, MIB-1, and proliferating cell nuclear antigen indices for primary tumors and metastases were as follows: 2/10 high-power field (hpf), 2.6% and 11%, respectively; 6/10 hpf, 7.8% and 16%, respectively. Staining for p53 protein was noted in 57% of primary tumors and 88% of metastatic tumors; a relative increase in p53 expression in metastases was noted in 83%. All but one of the primary and metastatic tumors were aneuploid. The most common treatments were radiation therapy and, for PRL cell carcinomas, dopamine agonist administration. Both treatments provided only palliation. Eighty percent of the patients died of metastatic disease 7 days to 8 years after the diagnosis of carcinoma; of these, 66% died within 1 year. At last follow-up, 20% of patients were alive with metastases 9-18 months after diagnosis.

CONCLUSIONS

Nearly all pituitary carcinomas present as functioning, microscopically atypical or mitotically active, invasive macroadenomas. By definition, after an interval related to their immunotype, all metastasize. The tumors show a greater tendency toward systemic metastasis than craniospinal metastasis and are associated with poor prognosis. Radiation and dopamine agonist therapy generally provide only palliation. Proliferation indices and p53 expression tend to be higher in metastases than in primary tumors. The current definition of pituitary carcinoma requires the demonstration of metastasis; however, high mitotic and MIB-1 labeling indices as well as p53 immunoreactivity suggest the diagnosis and appear to be of prognostic significance. A redefinition of aggressive pituitary tumors is proposed--one that facilitates the recognition of tumors prone to metastasis.

Pituitary Carcinomas

Pituitary carcinomas are defined by their metastatic growth. Most of them also invade into surrounding tissues. They should be classified by the site of their metastases (cerebrospinal, systemic, or combined) and by the presumable cell type of origin, respectively with the hormone being demonstrable by immunohistochemistry (adrenocorticotrophic hormone [ACTH], prolactin [PRL], growth hormone [GH], hormone-negative). Pituitary carcinomas develop from invasive adenomas. Nearly all tumors had been treated by surgery or X-ray before they metastasized. Since 1976, 37 cases demonstrated with modern methods were reported: 23 had metastasized into the brain or meninges, 10 showed extracerebral metastases, and 4 showed both types of metastases. In our collection of pituitary tumors, three carcinomas (0.13%) were identified: two with systemic metastases (one ACTH secreting and one PRL secreting) and one with meningeal dissemination and ACTH production. The diagnosis of pituitary carcinomas should be based on four criteria: a demonstrable metastasis, identification of the primary tumor as a pituitary tumor, similarity between the structure and immunohistological marker expression of metastasis and primary tumor, and exclusion of an alternative primary tumor.

Pituitary gland involvement of the sinonasal tract

Involvement of the upper aerodigestive tract by a pituitary adenoma is due either to downward extension of an intracranial tumor or to a tumor arising from ectopic (Rathke's pouch) remnants. Sites of predilection for the ectopic adenoma are headed by the sphenoid bone and sinus, followed by the soft tissue of the dorsal pharynx and clivus. Both invasive sellar and ectopic adenomas can be destructive, with the extracranial extension of pituitary adenomas being more locally aggressive. There have been no examples of metastasizing ectopic pituitary tumors.