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Numerous small lymphocytes with lobulated nuclei represent "cerebriform cells or flower cells" (arrows), and a few large lymphocytes with basophilic cells with vacuolated cytoplasm represent "hallmark cells" (arrowheads). Keywords: nucleophosmin-anaplastic lymphoma kinase; small cell variant; anaplastic lymphoma kinase-positive anapestic large cell lymphoma; leukaemic phase; droplet digital polymerase chain reaction EN nucleophosmin-anaplastic lymphoma kinase small cell variant anaplastic lymphoma kinase-positive anapestic large cell lymphoma leukaemic phase droplet digital polymerase chain reaction 241 243 3 12/27/21 20220101 NES 220101 The small cell variant of anaplastic large cell lymphoma (SC-ALCL) is a subtype showing unfavourable prognosis and accounting for 6% of ALCLs.1 SC-ALCL is defined as comprising two distinct tumour cell populations in immunohistochemistry: small cells staining negative or weakly positive for anaplastic lymphoma kinase (ALK) and cluster of differentiation 30 (CD30) protein; and large cells staining strongly positive for those proteins.2-4 Although the constitution of these two different cell populations might contribute to the poor prognosis, detailed characterisation of each population by molecular-based approaches has not been done due to the difficulty of cell separation from solid tumour samples. Characterisation of two tumour cell populations in the small cell variant of anaplastic lymphoma kinase-positive anaplastic large cell lymphoma. [Extracted from the article]

Anaplastic large cell lymphoma (ALCL) is an aggressive neoplasm of T- or null cell phenotype and is recognized as a distinct clinicopathologic subtype of non-Hodgkin lymphoma (NHL) in the revised World Health Organization (WHO) classification of hematopoietic neoplasms. It is rarely associated with leukemic phase. Most cases with leukemic involvement are the small cell variant of ALCL. These cases often lack the pleomorphism seen in the common variant of ALCL and may be misdiagnosed. We report a series of three patients who presented with leukemic phase ALCL. The patients included an 11-year-old boy, a 29-year-old man, and a 59-year-old woman. The clinical and pathologic features of these cases are reviewed. The patients in our case series with leukemic phase ALCL exhibited rare clinical features. The patients presented with massive extranodal disease involving cerebrospinal fluid (CSF), liver, spleen, lungs, and bone marrow. CSF involvement was documented morphologically as well as by flow cytometry in two patients. Two of the patients had small cell variant and the third patient had common type ALCL. The neoplastic cells in all three patients were ALK positive; however these patients died within months of diagnosis. Leukemic phase ALCL is rare, and behaves in an aggressive manner. Some, but not all, cases in the literature presenting with peripheral blood involvement had small cell variant ALCL, as seen in two of our cases. The leukemic phase of ALCL should be considered when a T-cell leukemia with unusual morphologic features is encountered. [ABSTRACT FROM AUTHOR]

Anaplastic lymphoma kinase positive, anaplastic large cell lymphoma (ALCL) is an uncommon T-cell non-Hodgkin lymphoma. A rare morphological variant-small cell variant of ALCL may pose diagnostic challenge especially when it presents primarily as a soft tissue mass. We present a rare case of small cell variant of ALCL in a 14-year-old female presented with arm swelling with emphasis on clinical, morphological and immunohistochemical aspects. Pathologists should be aware of this entity when considering a differential diagnosis of malignant round cell tumor as early and correct diagnosis has important clinical implications. [ABSTRACT FROM AUTHOR]