SMARCB1 (INI1) is one of the switch/sucrose nonfermentable (SWI/SNF) complexes whose loss is associated with several tumors. SMARCB1 (INI1)‐deficient intrathoracic neoplasms are extremely rare and known to be highly malignant and lethal. This report presents the case of a patient diagnosed with SMARCB1 (INI1)‐deficient intrathoracic neoplasm during chemotherapy for plasma cell myeloma. A 77‐year‐old male patient complained of cough, bloody sputum, and fever with an enlarged right lung mass and pleural effusion. His cytological examination revealed undifferentiated epithelioid and rhabdoid/plasmacytoid cells with bi‐ or multinucleation, vacuolization, mitosis, and pleomorphism. However, it was difficult to distinguish the relapse of plasma cell myeloma as atypical plasmacytoid cells were detected. Immunohistochemically, the neoplastic cells showed a loss of SMARCB1 (INI1) expression in the cell block of pleural fluid and in the right lung of the autopsy specimen. Further, the patient was diagnosed with SMARCB1 (INI1)‐deficient intrathoracic neoplasm of the right lung based on histological and autopsy findings. To the best of our knowledge, this is the first report of cytomorphology in a SMARCB1 (INI1)‐deficient intrathoracic neoplasm.

<b><i>Objective:</i></b> Recent advances in high-precision mammography and ultrasound screening have led to an increase in the detection of early lesions (ductal carcinoma in situ and small cancers) appearing as microcalcified lesions or microcystic images, and there needs to be an improvement in the accuracy of breast fine-needle aspiration biopsy (FNAB) assessing these lesions. The objective of this study was to investigate whether fractal analysis of Kirsch edge images for the tissue fragment inner structure (FKT) is useful in breast FNAB. FKT measures tissue fragment chromasia of hyperchromatic crowded tissue fragments (HCG), tissue fragment shape unevenness, and tissue fragment inner structure complexity. <b><i>Study Design Materials:</i></b> Nineteen epithelial tissue fragments of fibroadenoma (FA) from 7 patients and 52 tissue fragments of invasive breast carcinoma of no special type (IBC-NST) (grade 1–2) from 11 patients were assessed. First, tissue fragments were classified into small (smaller than 60 × 102 μm²), medium, and large (100 × 102 μm² or larger), and the appearance rate of each size was determined. Second, for FKT, the luminance value of tissue fragment chromasia, the unevenness and fractal value, and the tissue fragment inner structure complexity were determined. In statistical analysis, the Steel-Dwass test, nonlinear discriminant analysis, and receiver operating characteristic analysis were performed, setting the significance level at <i>p</i> &#x3c; 0.05. <b><i>Results:</i></b> “Unevenness of the tissue fragment shape,” “fractal value of the tissue fragment shape,” and “fractal value of the tissue fragment inner structure” were significantly higher in small and large tissue fragments in IBC-NST compared with those in FA. The specificity and sensitivity were the highest (100%) in small tissue fragments in multivariate analysis using 4 variables (“luminance value of tissue fragment chromasia,” “unevenness of tissue fragment shape,” “fractal value of the tissue fragment shape,” and “fractal value of the tissue fragment inner structure”). <b><i>Conclusion:</i></b> FKT, which evaluates “tissue fragment darkness,” “tissue fragment shape unevenness,” and “tissue fragment inner structure complexity” focusing on small tissue fragments of HCG in breast FNAB, is useful as a system that assists cytopathological assessment of breast FNAB.

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Anaplastic lymphoma kinase-positive anaplastic large cell lymphoma (ALK+ ALCL) is characterised by large lymphocyte-like cells with abundant cytoplasm and variable-shaped nuclei, often resembling horseshoes or kidneys. These cells have a specific genetic translocation involving the ALK gene and are positive for ALK and CD30 by immunohistochemistry. 1 In children, ALK+ ALCL is the most common subtype of T-cell lymphoma, accounting for 10%-30% of lymphomas. ALK+ ALCL exhibits a wide range of morphological patterns, with the common variant comprising 60% of cases, followed by lymphohistiocytic (10%), small-cell (5%-10%), and Hodgkin-like (3%) variants. 2 In small cell variant ALCL (SC-ALCL), large hallmark cells are few with the preponderance being small-to medium-sized tumour cells.Tumour cells in peripheral blood indicate the leukaemic phase, which is associated with poor prognosis. Among the morphological variants, patients with SC-ALCL often show the leukaemic phase, thus accurate and prompt diagnosis is essential for effective treatment. 3 How to cite this article: Shimaguchi C, Mizuguchi K, Fujita K, Shimoda T, Ikeda H. Cytological examination of peripheral blood cell block to diagnose small cell variant ALK-positive anaplastic large cell lymphoma.