Colloid cyst of the third ventricle: cytomorphologic features on stereotactic fine-needle aspiration

Intraventricular sizeable colloid cyst with atypical radiological features: A case report and evidence-based review

Colloid cysts are benign intracranial lesions, typically located in the anterior portion of the third ventricle near the interventricular foramina of Monro. The cysts usually consist of an epithelial lining filled with viscous gelatinous material of various components. Colloid cysts are generally asymptomatic, but once symptomatic, they can present in a variety of ways, including headaches, vomiting, visual and memory problems, and vertigo. Colloid cysts present classically on imaging as a well-delineated hyperattenuating lesion on unenhanced radiological modalities. Herein, we report a case of a patient who presented with hydrocephalus caused by a sizeable colloid cyst which demonstrated atypical imaging findings in the form of hypodensity on CT and hyperintensity on T2WI, making them difficult to identify and easy to miss. Although this atypical imaging appearance is uncommon with yet unknown true incidence, it is prudent to be aware of it because early management of colloid cysts has a favorable outcome, in contrast to untreated cysts that are associated with higher rates of morbidity and mortality. Additionally, we provide a comprehensive, evidence-based review of the medical entity of intracranial colloid cysts with highlights of current postulated pathological theories and management algorithms.

First reported case of hydrocephalus in jointly diagnosed bacterial meningitis and a colloid cyst: how Ockham's razor became Hickam's dictum

We report the first case in the literature of acute hydrocephalus due to a simultaneous diagnosis of bacterial (not asceptic) meningitis and a colloid cyst. Diagnosing disease is the cornerstone skill of a medical practitioner. Both education and experience allow for sharpening of this skill throughout years of medical practice. Disease is fraught with nuances and inconsistencies which can render an accurate diagnosis a difficult task. Medical practitioners can be guilty of cognitive biases such as Ockham's razor. We present the case of a patient with an initial diagnosis of obstructive hydrocephalus secondary to a colloid cyst. However, pneumococcal meningitis blunted Ockham's razor in favour of Hickam's dictum.

Endobronchial ultrasound-guided transbronchial needle aspiration diagnosis of mediastinal lymph node metastasis of mucinous adenocarcinoma: arborizing stromal meshwork fragments as a diagnostic clue

Endobronchial Ultrasound-Guided Transbronchial Needle Aspiration (EBUS-TBNA) is a reliable and accurate method for the diagnosis of mediastinal metastases in patients with pulmonary and extrathoracic neoplasms. We report the cytopathologic findings of a case of metastatic signet-ring cell carcinoma with abundant extracellular mucin production in the mediastinal lymph nodes of a 41-year-old woman, who presented with nausea, abdominal pain, and weight loss. Imaging studies showed a renal mass, numerous lung nodules, and mediastinal and retroperitoneal lymphadenopathy. EBUS-TBNA of level 4R and 7 lymph nodes showed abundant, thick, "clean" mucus with entrapped ciliated bronchial cells, rare histiocytes, and fragments of cartilage. No neoplastic cells could be identified in Diff-Quik®-stained smears during the rapid on-site evaluation, but rare signet-ring cells were identified in the Papanicolaou-stained smears and cellblock sections. A distinctive feature of the aspirates was the presence of large branching (arborizing), "spidery" stromal fiber meshwork fragments. These stained metachromatically (magenta) with Romanowsky-type stains and cyanophilic to orangeophilic with Papanicolaou stains and showed occasional attached bland spindle cells, but had no capillary lumina or CD31-staining endothelial cells. The tumor cells were strongly and diffusely positive for CEA, CDX2, CK7, CK20, and MUC2, supporting the diagnosis of a metastatic signet-ring cell adenocarcinoma, most likely of gastrointestinal origin. We believe that the presence of the large spidery stromal fiber fragments is a useful clue to the presence of a mucinous neoplasm in EBUS-TBNA and allows the differentiation of the neoplastic mucus from contaminating endobronchial mucus.

Pineal gland lesions: a cytopathologic study of 20 specimens

BACKGROUND

Pineal gland lesions are rare, with only a few cytologic descriptions occurring in the literature, according to the authors' knowledge. The current article describes the cytopathologic characteristics of 20 such lesions with discussion of differential diagnoses.

METHODS

Cytologic material was obtained either by fine-needle aspiration biopsy (FNAB) under stearotactic radiologic guidance or by touch imprinting (TI) at the time of frozen sectioning. The 20 specimens include pineoblastoma (five specimens), pineocytoma (four specimens), astrocytoma (three specimens), germ cell tumor (three specimens), meningioma (one specimen), epidermoid cyst (three specimens), and pineal cyst (one specimen). Smears were stained with Diff-Quik and with Papanicolaou and hematoxylin and eosin stains. In selected specimens, immunoperoxidase (IPOX) stains were performed on cell block sections using synaptophysin, neuron-specific enolase, placental alkaline phosphatase, glial fibrillary acidic protein, leukocyte common antigen, cytokeratins, and human chorionic gonadotropin antibodies.

RESULTS

Several cytomorphologic characteristics unique to each lesional category with occasional overlapping features were observed. The unique features included the following: small, hyperchromatic, round to oval cells with frequent rosetting (pineocytoma), with a few specimens in addition showing hypercellularity, crowding, mitoses, and necrosis (pineoblastoma); pleomorphic round cells in a fibrillary background (astrocytoma); large polygonal cells with prominent nucleoli and clear cytoplasm (germ cell tumor); spindled fibroblastic cells (meningioma); anucleate squames and mature squamous cells (epidermoid cyst); and small uniform polygonal cells (pineal cyst). When necessary, IPOX studies supported the morphologic diagnoses.

CONCLUSIONS

FNAB and TI cytology were found to provide a rapid and reliable diagnosis of pineal lesions. This is particularly important when dealing with minute amounts of tissue material. Both techniques appeared to provide equally good cytomorphology on smears. IPOX studies played an important complementary role in difficult cases when performed on cell blocks.