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Central nervous system (CNS) hematologic malignancies, whether primary or secondary, are uncommon and their clinical presentations vary. Intravascular lymphoma (IVL) is a very rare, aggressive systemic malignancy that is often difficult to diagnose and susceptible to early CNS involvement. Blast crisis in myeloid leukemias can cause widespread neoplastic emboli. Here, we report two adult patients (72 years and 22 years of age) who presented with altered mental status followed by rapid decline in their conditions leading to death. No prior significant medical history was present for either patient, while acute myeloid leukemia was diagnosed in the younger patient immediately before death. During autopsy, we performed imprint and squash preparations, and frozen sections of representative cerebral cortex, cerebellum, leptomeninges, and the pituitary gland. In the older patient, presence of IVL was readily detected on cytologic preparations. Diffuse involvement of brain vasculature and perivascular parenchyma with acute myeloid leukemia was identified in the other patient. Although examination of the fresh brain is not routinely performed during autopsy, these cases are presented to illustrate that imprint and squash preparations can provide a rapid and reliable provisional autopsy diagnosis in select patients.

Pax-2 is a homeogene expressed during kidney development. Its expression in renal cell carcinoma (RCC) has been previously evaluated in histologic samples with a high sensitivity and specificity. Here, we investigated the utility of Pax-2 immunohistochemistry (IHC) for RCC in cytologic material, in comparison with a variety of other neoplasms. Pax-2 IHC was performed on cell block sections of 33 RCCs (14 primary, 19 metastatic) and 35 non-RCC malignancies, including 26 carcinomas, five mesenchymal tumors, one neuroblastoma, two melanomas, and one lymphoma, from fine-needle aspirations and body fluids. The presence or absence of nuclear staining and its intensity and distribution in positive cases were evaluated. Of 33 RCCs, Pax-2 was positive in 20 (61%) and negative in 13 (39%). All staining was nuclear, with an admixture of weakly or strongly staining nuclei. Only an endometrial adenocarcinoma was positive in the non-RCC group. The sensitivity and specificity of Pax-2 IHC for RCC were 61 and 97%, respectively. Pax-2 is a moderately sensitive and highly specific marker for RCC in cytologic material, with a lower sensitivity compared with tissue sections, likely due to a patchy expression pattern, and should be included in the immunohistochemical work-up of malignancies.

The epithelioid variant of malignant peripheral nerve sheath tumor (eMPNST) is an extremely rare soft tissue neoplasm comprising less than 5% of all MPNSTs. It is distinguished cytomorphologically from a conventional MPNST by the presence of polymorphous round epithelioid cells arranged in loose clusters with or without spindled tumor cells. These features pose a diagnostic challenge because the differential diagnosis involves a variety of mesenchymal and non-mesenchymal tumors including epithelioid sarcoma, sclerosing epithelioid fibrosarcoma, malignant rhabdoid tumor, chordoma, metastatic carcinomas, and melanoma. Thus, it may become imperative to perform immunochemical stains on cell blocks of FNA aspirates to arrive at definitive diagnosis. Reports describing the cytologic features of eMPNST are rare. Herein, we report a case of eMPNST with focus on cytomorphologic and cytoimmunochemical features and differential diagnosis.

Small-cell carcinoma (SmC) and high-grade non-Hodgkin's lymphoma (NHL) are aggressive neoplasms that require prompt diagnosis and treatment. An immediate diagnosis can be obtained using fine-needle aspiration biopsy (FNAB) material from lymph nodes (LNs), which are clinically or radiologically suspicious for tumor involvement. However, in aspirates from LNs, the cytologic distinction of SmC from NHL can be challenging. The purpose of this study was to evaluate the usefulness of various cytologic features that can be used during a rapid on-site evaluation to differentiate these two entities. Twenty-seven metastatic SmC and 50 NHLs cases diagnosed by FNAB of LNs were reviewed. All NHL diagnoses (neck, 29; abdomen, 9; axilla, 6; groin, 5; and parotid, 1) were confirmed with tissue sections, flow cytometry, or immunohistochemistry. These cases were classified as follicular, 21 (42%); diffuse large B cell, 13 (26%); small lymphocytic, 7 (14%); mantle cell, 4 (8%); anaplastic large cell, 2 (4%); and 1 each (2%), Burkitt, lymphoplasmacytic, and peripheral T-cell lymphomas. Immunochemistry confirmed the cytologic diagnoses of all SmC cases (neck, 16; mediastinum, 9; abdomen, 1; and axilla, 1) with either positive chromogranin or synaptophysin. All specimens were reviewed independently by three cytopathologists who were unaware of the original diagnoses. The presence and proportion of single (noncohesive) tumor cells, lymphoglandular bodies, nuclear fragments, paranuclear blue inclusions, nuclear molding, evenly dispersed fine-granular chromatin, crush artifact, and composition of cell clusters (monomorphic vs. polymorphic) were statistically evaluated. The presence of evenly dispersed fine-granular chromatin, paranuclear blue inclusions, and nuclear fragments was each statistically significant in differentiating SmC when compared with NHL (P < 0.01). The remaining features were not significant in distinguishing SmC from NHL in LN aspirates. The identification of distinct cytologic findings such as evenly dispersed fine-granular chromatin, paranuclear blue inclusions, and nuclear fragments can be a valuable aid to accurately diagnose and differentiate metastatic SmC from NHL in FNAB preparations from LNs. Diagn. Cytopathol. 2004;31:229–234. © 2004 Wiley-Liss, Inc.

Meningiomas are benign tumors derived from arachnoid cells. Most commonly an intracranial lesion, meningiomas may be found extracranially in various anatomic sites. A 23-yr-old white female presented with left-sided palpable mass located submucosally in the floor of the mouth. CT scan revealed no evidence of mass elsewhere in the head and neck region. Fine-needle aspiration cytology (FNAC) showed loose and cohesive cellular fragments with lobular growth pattern and uniform round or ovoid cells. The diagnosis of low-grade salivary gland neoplasm, not further classified, was made. The tumor was locally excised. The differential diagnoses of an extracranial meningioma and pleomorphic adenoma were discussed at the frozen section. Based on light microscopic, immunohistochemical, and electron microscopic (EM) findings, the final diagnosis of an ectopic meningioma was rendered. Ectopic meningiomas may pose a diagnostic challenge to clinicians and cytopathologists. It is easily forgotten in the list of differential diagnosis at an ectopic site. Primary ectopic meningioma in a region containing salivary gland(s) may mimic benign and low-grade malignant salivary gland tumors in FNAC.

Differential diagnosis of primary and metastatic carcinomas of the liver can be problematic and may require immunohistochemical work-up. Recently, new immunohistochemical markers have been introduced with promising results in this area. We studied three of these markers, human hepatocyte antibody (HepPar-1), human epithelial-related antigen (MOC-31), and thyroid transcription factor-1 (TTF-1), in cell-block sections of fine-needle aspirations from 30 hepatocellular carcinomas and 27 metastatic carcinomas from various sites. Of 27 metastatic carcinomas, all but one were positive for MOC-31 and, all but one were negative for HepPar-1. TTF-1 was positive only in the nuclei of metastatic poorly differentiated neuroendocrine carcinoma from the lung. Of 30 hepatocellular carcinomas, 26 were positive for HepPar-1 and all were negative for MOC-31, while TTF-1 showed cytoplasmic staining in 23 cases. HepPar-1, MOC-31, and TTF-1 are complementary markers in the differential diagnosis of primary and metastatic carcinomas of the liver, with high sensitivity and specificity.