Pathobiologic study of pituitary tumors: report of 62 cases with a review of the recent literature

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.

Unusual case of metastatic neuroendocrine tumor

OBJECTIVE

To report a rare case of metastatic growth hormone (GH)-secreting pituitary carcinoma causing acromegaly.

METHODS

We present a case report and review the available literature on this topic.

RESULTS

A 68-year-old woman presented with persistent acromegaly after treatment for a GH-secreting pituitary adenoma. Evaluation of long-standing cervical adenopathy revealed findings consistent with a metastatic neuroendocrine tumor. Further work-up revealed additional thyroid, parathyroid, and cervical masses. After operative treatment including total thyroidectomy, subtotal parathyroidectomy, partial thymectomy, and right modified radical neck dissection, the patient's symptoms diminished, and her GH levels approached the normal range. Surgical pathology findings were consistent with a GH-secreting pituitary carcinoma metastatic to the cervical lymph nodes, multinodular thyroid hyperplasia with a focus of papillary microcarcinoma, and parathyroid hyperplasia.

CONCLUSION

Overall, pituitary carcinomas are extremely rare. To date, about 100 cases have been reported in the world's literature, and of these, only 19 cases originated from GH-secreting cells. Our examination of the symptoms, signs, diagnosis, and treatment of our patient, in comparison with the previously reported cases, should enhance awareness of this unusual disease process.

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.

Widespread neuroendocrine malignancy within the central nervous system: a diagnostic conundrum

A 75 year old female presented with a sellar tumour, and was subsequently found also to have a cauda equina tumour, a parietal dural tumour, a pontine tumour, an intradural spinal tumour, and several vertebral body tumours. Histological examination revealed a neuroendocrine tumour forming cell nests surrounded by reticulin. There was moderate nuclear pleomorphism, prominent mitoses, and focal necrosis. Immunohistochemistry showed diffuse positive staining with cytokeratins, chromogranin and 5-hydroxytryptamine, and focal positive staining with S100. This case is an unusual and ultimately insoluble, diagnostic problem; however, the differential diagnoses include pituitary carcinoma, malignant paraganglioma, and atypical carcinoid.

A longitudinal study of the effects of surgery, radiation, growth hormone, and orthodontic therapy on the craniofacial skeleton of a patient evidencing hypopituitarism and a Class II malocclusion: report of a case

Facial growth is an important factor for the orthodontists in the timing of treatment of the patient with a Class II malocclusion who has a potential for retarded growth. This patient had an isolated idiopathic growth hormone deficiency and hypothyroidism and was treated during a circumpubertal growth spurt in two phases. The first phase involved a functional appliance and the second was accomplished with fixed appliances. The case report affords one of the rare opportunities to document and analyze the multifactorial effects of surgery, radiation, growth and thyroid hormones, and orthodontic treatment on the craniofacial growth of a patient evidencing a Class II, Division 1 malocclusion (retrognathic mandible). Hand-wrist, panoramic, cephalometric radiographs, dental, and skeletal height and weight measurements are employed. Six-year posttreatment dental and craniofacial skeletal changes and management problems are presented as well.

The biology and pathology of selected skull base tumors

This paper describes the pathobiology of some of the more common skull base tumors. In addition to clinicopathologic features, emphasis is placed upon methods of diagnosis utilizing immunoperoxidase stains and molecular markers that may or may not impact upon prognosis.

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.

Human pituitary somatotroph adenoma and prolactinoma: an ultrastructural and immunoelectron microscopical study

17 cases of pituitary somatotroph adenoma and 38 cases of prolactinoma were studied with electron microscopy and immunoelectron microscopy using protein A-gold complex. 4 adenomas were shown by immunoelectron microscopy to contain simultaneously growth hormone (GH)-producing and prolactin (PRL)-producing cells. 6 cases were classified as densely granulated GH adenomas and 11 as sparsely granulated variant, whereas only 3 adenomas out of 38 prolactinomas were identified as densely granulated adenomas. The present study showed that not all cells with fibrous bodies possessed secretory granules positive for GH, and in some cells with fibrous bodies PRL-producing granules were also detected. Misplaced exocytosis was found frequently in the sparsely granulated prolactinomas. From these findings it may be suggested that fibrous bodies are not a morphological feature characteristic of pituitary somatotroph adenomas.

Light bodies in human pituitary adenomas

Light bodies are large cytoplasmic granules originally described in the gonadotrophic cells of the rat pituitary gland. In order to determine whether similar bodies occur in the human anterior pituitary gland, 89 pituitary adenomas and periadenomatous tissue from 20 cases were examined by transmission electron microscopy. Double membrane bound bodies with filamentous internal structure identical to rodent light bodies were identified in 10 hormone-producing adenomas: 5 PRL, 1 PRL-GH, 2 GH, and 2 ACTH-producing tumours. No light bodies were found in the remaining 79 tumours nor in the pituitary cells in periadenomatous tissue from 20 cases. These results show that some human pituitary adenomas may contain light bodies identical to those seen in gonadotrophs of rat pituitary.

Endocrine inactive pituitary carcinoma metastasizing to cervical lymph nodes: a case report

A 64-year-old woman experienced an episode of disorientation in relation to time, place, and people, as well as of visual defect and impaired balance. Physical examination showed a bitemporal hemianopsia and truncal ataxia. Computerized tomography of the skull revealed a sellar mass consistent with the diagnosis of pituitary adenoma. The patient progressively lost consciousness and died. At postmortem examination, a pituitary neoplasm with arachnoid metastases was present. Metastatic cervical lymph nodes were also detected. Histologic aspects of the primary tumor and of lymph node metastases were quite similar. Immunohistochemical investigation revealed the epithelial origin of the neoplasm and failed to disclose endocrine activity. At ultrastructural examination, the cells of the primary tumor and of the metastases lacked specific granules. These findings support the evidence of a primary metastasizing pituitary carcinoma.

Ectopic anterior pituitary corticotropic tumour in a six-year-old boy. Histological, ultrastructural and immunocytochemical study

The report documents a silent, oncocytic, ACTH-producing ectopic anterior pituitary tumour in a 6-year-old boy. The invasive intrahemispheric neoplasm had no connection with the pituitary gland, the sella turcica or the sphenoid sinuses. The apparent similarities existing between this tumour, some choroid plexus carcinomas and steroid-producing neoplasms are discussed.

ACTH-producing microadenoma of the pituitary in a young female infant with Cushing's disease: report of a case including immunocytologic and ultrastructural studies

A female infant, younger than any other case in the literature, with ACTH-producing microadenoma of the pituitary is reported. She had full-blown symptoms and signs as well as laboratory evidence of Cushing's disease. The tumor was investigated by histology, immunocytology (avidin-biotin-peroxidase complex technique), and electron microscopy. The possibility that the tumor was derived from the fetal intermediate lobe is discussed.