Cytological features of the native pineal gland in intraoperative squash preparations

Abstract

The pineal gland, also known as the conarium, is one of the six circumventricular organs of the central nervous system.1 It has a location in the midline within the anterior quadrigeminal cistern, and lies above the superior colliculi, at the posterior recesses of the third ventricle. The pineal gland has unique histology among central nervous system tissues. It consists of prominent lobules surrounded by connective tissue septa. The pineocytes within the lobules form sheets within a fibrillary background, punctuated by distinctive pineocytic rosettes with central fibrillary cores. A population of astrocytes forms a loose network among the pineocytes. The pineocytes demonstrate immunoperoxidase expression of synaptophysin and neurofilament protein, while the supporting astrocytes are positive for glial fibrillary acid protein and S100 protein. Ultrastructural analyses of pineocytes have revealed morphological evidence of neurosensory differentiation by the presence of vesicle-crowned rodlets, fibrous filaments and paired twisted filaments, and also of neuroendocrine differentiation with dense core granules. 3After puberty, mineralized concretions known as corpora arenacea (or brain sand) become present and accrue with age. This is accompanied by gliosis and cystic change which gradually replace the cellular pineocytic population. 1Since the discovery of melatonin more than half a century ago, great strides have been made in characterization of the structure and function of the pineal gland.4 However to date, the cytological features of the normal pineal gland, as seen in intraoperative squash preparations has not been well illustrated in the literature.Intraoperative smear cytology using the technique of squash preparations is very commonly practiced in surgical neuropathology. This method provides superior morphological preservation in the neurosurgical setting where biopsies are often limited in size and the tissue is particularly vulnerable to freezing artefact.Unfortunately, the smear cytology features of the pineal gland are not familiar to many surgical pathologists, perhaps due to the relative rarity of lesions involving the pineal area, and the small size of the gland, rendering it readily overrun and destroyed by aggressive neoplasms.As lesions of the pineal region are being increasingly targeted by stereotactic biopsies and submitted for intraoperative diagnosis, knowledge of the cytological features of the normal pineal gland as encountered in the intraoperative setting is of importance. An ability to distinguish normal pineal tissue from lesional tissue is pivotal in intraoperative management; the finding of normal tissue prompts further surgical sampling to identify the actual lesion under the same anesthetic procedure.In this report, we describe the features of the native pineal gland on intraoperative squash preparation, as fortuitously encountered in a biopsy of a pineal lesion in a young female.The intraoperative smears were moderately cellular with cohesive clumps of cells within a fibrillary ba...

Pitfalls in Diagnosis of Intraoperative Squash Cytology of Central Nervous System Lesions

“…The search for a background of lymphoglandular bodies may be helpful for the diagnosis of lymphoma. 1,2,4,8 Central neurocytoma usually exhibits cellular, monomorphic round cells with thin-walled capillary network. They have oligodendroglia-like cell morphology in a neuropil background.…”

Cytologic features of the normal pineal gland on squash preparations

“…Nuclei are round and bland with delicate chromatin . Calcium concretions, known as corpora arenacea or “brain sand,” form after puberty and accumulate with age . A review of the cytology literature showed one article that described normal pineal gland features in an adult female .…”

“…Calcium concretions, known as corpora arenacea or “brain sand,” form after puberty and accumulate with age . A review of the cytology literature showed one article that described normal pineal gland features in an adult female . The authors noted the following features: moderate cellularity, a fibrillary background, sheets and rosettes of pineocytes with central fibrillary cores, discohesive peripheral cells, a delicate capillary network, and calcifications.…”

“…Intraoperative smear cytology using squash preparations is a commonly used cytological technique as it provides better morphological interpretation than a small tissue biopsy which may be vulnerable to freezing artifact. However, due to the rarity of primary pineal lesions and the tendency of the small gland to be destroyed by more aggressive neoplasms, many surgical pathologists are not familiar with cytological features of the normal pineal gland . Lee et al described the cytological features of a surgical pineal specimen from a young female .…”

“…However, due to the rarity of primary pineal lesions and the tendency of the small gland to be destroyed by more aggressive neoplasms, many surgical pathologists are not familiar with cytological features of the normal pineal gland . Lee et al described the cytological features of a surgical pineal specimen from a young female . However, to the best of our knowledge, a comprehensive study of cytologic features in patients of varying ages has not yet been performed.…”