The cell block (CB) is a routine procedure in cytopathology that has gained importance because of its pivotal role in diagnosis and ancillary studies. There is no precise review in the published literature that deals with the various methods of preparation of CB, its utility in diagnosis, immunocytochemistry (ICC) or molecular testing, and its drawbacks. An extensive literature search on CB in cytology using internet search engines was performed for this review employing the following keywords: cell block, cytoblock, cytology, cytopathology, methods, preparation, fixatives, diagnostic yield, ancillary and molecular studies. Ever since its introduction more than a century ago, the CB technique has undergone numerous modifications to improve the quality of the procedure; however, the overall principle remains the same in each method. CBs can be prepared from virtually all varieties of cytological samples. In today's era of personalized medicine, cytological specimens, including CBs, augment the utility of cytological samples in analysing the molecular alterations as effectively as surgical biopsies or resection specimens. With the availability of molecular targeted therapy for many cancers, a large number of recent studies have used cytological material or CBs for molecular characterization. The various techniques of CB preparation with different fixatives, their advantages and limitations, and issues of diagnostic yield are discussed in this review.

Across several geographical settings, sarcoidosis and infections are the most common causes of pulmonary granulomas diagnosed in pathological specimens. Fungi are more commonly identified than mycobacteria in the USA, whereas the reverse is true in other countries. A definite aetiology cannot be demonstrated in more than a third of all cases of pulmonary granulomas, even after histological examination. These findings highlight the need to submit material for histology as well as cultures in all cases in which granulomatous disease enters the differential diagnosis.

Background To determine human papillomavirus (HPV) types by polymerase chain reaction (PCR)-reverse line blot assay and examine the concordance between HPV by Hybrid Capture 2 (HC2) and PCR on self-collected vaginal and physician-collected cervical samples and cytology. Methods This was a cross-sectional study of 546 sexually active women aged ≥30 years with persistent vaginal discharge, intermenstrual or postcoital bleeding or an unhealthy cervix. Participants self-collected vaginal samples (HPV-S) and physicians collected cervical samples for conventional Pap smear and HPV DNA (HPV-P) testing and performed colposcopy, with directed biopsy, if indicated. HPV testing and genotyping was done by HC2 and PCR reverse line blot assay. Concordance between HC2 and PCR results of self- and physician-collected samples was determined using a Kappa statistic (κ) and Chi-square test. Results Complete data were available for 512 sets with 98% of women providing a satisfactory self-sample. PCR detected oncogenic HPV in 12.3% of self- and 13.0% of physician-collected samples. Overall, there was 93.8% agreement between physician-collected and self-samples (κ = 76.31%, 95% confidence interval [CI]: 64.97–82.29%, p = 0.04)—complete concordance in 473 cases (57 positive, 416 negative), partial concordance in seven pairs and discordance in 32 pairs. The sensitivity, specificity, positive predictive value (PPV) and negative predictive value (NPV) of self-sampling for detection of cervical intraepithelial neoplasia (CIN)2+ disease were 82.5%, 93.6%, 52.4% and 98.4%, respectively; for physician-sampling they were 87.5%, 93.2%, 52.2% and 98.9%, respectively; and for cytology they were 77.5%, 87.3%, 34.1% and 97.9%, respectively. Concordance between HC2 and PCR was 90.9% for self-samples (κ = 63.7%, 95% CI: 55.2–72.2%) and 95.3% for physician-collected samples (κ = 80.4%, 95% CI: 71.8–89.0%). Conclusions Self-HPV sampling compares favourably with physician-sampling and cytology. A rapid, affordable, HPV self-test kit can be used as the primary method of cervical cancer screening in low-resource situations.

Giant cell tumor of tendon sheath (GCTTS) is a unique soft tissue lesion of the hands and feet. As the cytomorphological features of this lesion are rarely documented, the spectrum of cytomorphological features in 20 cases of GCTTS seen in fine-needle aspiration (FNA) smears are presented. Patients were in the 12-64-yr age group with an equal sex ratio. Fingers or thumb were the commonest site (16 cases), followed by foot (3 cases) and palm (1 case). FNA smears were cellular and composed of varying proportions of stromal and giant cells. Stromal cells showed a dispersed arrangement and were polygonal to spindle shaped. Nuclear grooves and convolutions were found in some of the stromal cells in all cases. Intranuclear cytoplasmic inclusions were occasionally seen. Polygonal cells with round nuclei and nucleoli having abundant cytoplasm, along with binucleate forms, were also found in all cases. Histological sections were available in 10 cases and corroborated the cytological features. Hemosiderin-laden macrophages (11 of 20 cases) and abundant foamy vacuolation of stromal cells (3 of 20 cases) were also observed in FNA smears. In tissue sections, both features were seen in all cases, but with a patchy distribution. The cytological features of GCTTS are uniform, and FNA cytodiagnosis is possible.

ADC values provide a non-invasive means to predict the nuclear grade and histological subtype of RCC. Cellularity and morphology are other tumor attributes contributing to the variation in ADC values of RCCs.

The criteria outlined by TPS facilitated the standardisation of urine cytology reporting and significantly increased the sensitivity of diagnosing HGUC.

Background: Rosai-Dorfman disease (RDD) is a rare benign idiopathic histiocytic proliferation. Most commonly reported cases are lymph nodal. Only 30-40% of cases occur in extranodal sites. Although the morphological features of RDD are well documented, there is limited information about the morphometric variations in the histiocytes of this entity. Method: Twenty-two cases of RDD diagnosed on fine-needle aspiration cytology (FNAC) were retrieved from the archives. Both Papanicolaou- and May-Grünwald-Giemsa-stained slides were available for evaluation in all cases. Nuclear area, diameter and histiocyte size were measured taking reactive histiocytes as controls. Results: Among the 22 patients (male/female ratio 3:2; age range 5-55 years, mean 26 years), 3 cases were extranodal and 19 cases were nodal. The nodal sites included cervical, axillary, inguinal and submandibular lymph nodes. The extranodal sites were the retroperitoneum, mediastinum and skin. The most common clinical presentation was enlarged lymph nodes. Cytological features included numerous large benign histiocytes with emperipolesis. All the morphometric parameters were significantly (p < 0.01) higher in RDD histiocytes than in histiocytes in the reactive lymph node. Conclusions: In view of the rarity of the disease and the variable clinical presentation in RDD, accurate diagnosis is necessary. This is the first study to document the morphometric parameters of RDD histiocytes and their comparison with histiocytes in the reactive lymph node.

PD-L1 ICC can be performed on LBC processed smears, with certain challenges in interpretation inherent to LBC smears and their processing methods. Nevertheless, they represent a potential resource for ICC, especially when alternate histology material is not available. Future studies are required to validate the predictive value of PD-L1 ICC on LBC smears.