The Difficulties and Ease of Diagnosing Anaplastic Large Cell Lymphomas on Cytology

Introduction and Objectives

Anaplastic large cell lymphoma (ALCL), a unique non-Hodgkin lymphoma (NHL), is a CD30-positive neoplasm of T-cell lineage. Its distinctive yet variable cytomorphology makes diagnosing fine needle aspiration cytology (FNAC) challenging. This study was undertaken to study the cytomorphology and the utility of immunocytochemical (ICC) stains on cytology in ALCL and to discuss their morphological differential diagnosis.

Materials and Methods

The present study was conducted in the Department of Pathology of a tertiary care center. A retrospective review was done from January 2017 to July 2022, and all histopathologically and immunohistochemically (IHC) diagnosed cases of ALCL were taken and correlated with the cytological diagnosis.

Results

Twenty-one cases of histopathology examination and IHC-proven cases of ALCL were retrieved from the departmental archives and reviewed. The ages ranged from 3 to 80 years (median age 28 years). Commonly noted cytomorphologic features included singly dispersed large pleomorphic cells, hallmark cells, and Reed-Sternberg-like cells. CD15, CD30, epithelial membrane antigen, and anaplastic lymphoma kinase-1 were some of the ICC stains used in this study. All 21 cases had cytology correlation. Fourteen cases had concordant cyto-histological correlation. Seven cases of histopathologically proven ALCL were reported as Hodgkin lymphoma (HL) in three, ALCL/anaplastic diffuse large B-cell lymphoma, HL/ALCL, poorly differentiated carcinoma, and NHL in one case each on cytology.

Conclusion

ALCL has a reasonably distinct cytomorphologic appearance and ICC staining pattern, and a careful interpretation of both helps arrive at a reliable FNAC diagnosis.

Pitfalls in Lymph Node Fine Needle Aspiration Cytology

BACKGROUND

Fine needle aspiration cytology (FNAC) is an accurate, minimally invasive, and cost-effective biopsy method for enlarged lymph nodes. While the role of lymph node FNAC in the diagnosis of infectious or reactive conditions and metastatic malignancy is unquestioned, differing views still exist on its role in the diagnosis of lymphoma. Nevertheless, regardless of the practice setting, pitfalls and potential for error exist, and it is incumbent upon the pathologist to be aware of these pitfalls, as this is the first line of defence against errors.

SUMMARY

This discussion will focus on potential interpretational errors, specifically highlighting scenarios leading to false-negative and false-positive diagnosis and errors in tumour classification, with an emphasis on cytomorphology. Potential entities that may fly below the radar of the pathologist - so-called off-radar entities - are also discussed, as a reminder to consider broad differentials in cases with unusual morphologic features. Some reasons for false-negative diagnoses include low-grade lymphomas that mimic a mixed, polymorphous reactive lymphoid population or aspirates with a paucity of lesional cells, through either sampling error or the intrinsic nature of the entity, e.g., nodular lymphocyte predominant Hodgkin lymphoma. Some of the potential causes of false-positive diagnoses that are discussed include viral-associated lymphadenopathy, Kikuchi-Fujimoto lymphadenitis, or benign adnexal lesions mimicking metastatic malignancy. Errors in tumour classification covered include metastatic carcinoma, sarcoma, melanoma, and lymphoma mimicking each other, and Hodgkin lymphoma and its mimics. Finally, less common entities such as follicular dendritic cell sarcoma and others are briefly mentioned, to remind us of conditions that may slip under our diagnostic radar.

KEY MESSAGES

A systematic review of diagnostic pitfalls and traps is elucidated here, with some tips to avoid these traps. The triple approach to the diagnostic workup is emphasised, which includes rigorous clinicopathologic correlation, attention to cytomorphology, and judicious application of ancillary tests.

Cytological Diagnosis of Aggressive Small-Cell Lymphomas

BACKGROUND

Despite their sometimes deceivingly bland appearance, some small-cell lymphomas are very aggressive and the prognosis of patients depends on a prompt diagnosis that allows the initiation of appropriate therapy.

SUMMARY

The present review discusses the salient cytological features of the most common aggressive small-cell lymphomas and then proceeds to analyze their main diagnostic criteria, including the usage of ancillary techniques.

KEY MESSAGES

Lymph node fine-needle aspiration cytology is a fast, safe, cheap, minimally invasive, and accurate procedure that can be used for a prompt and accurate diagnosis of lymphomas.

Diagnostic Challenges of Anaplastic Large Cell Lymphoma in a Resource-Limited Setting: A Case Report and Literature Review

Anaplastic large cell lymphoma (ALCL) is a rare variety of non-Hodgkin's lymphoma with diverse morphologic variants. Due to the similarity of the different variants with other lymphoma entities, misdiagnosis may be inevitable when immunohistochemical and cytogenetic techniques are not available and histology alone is employed. We report a case of a 43-year-old woman with a seven-month history of neck swelling which was complicated by ulceration of the mass and pathological fracture of the right clavicle after two months delay in arriving at a correct diagnosis. Several attempts to arrive at definitive diagnosis using histology alone gave divergent reports which all misdiagnosed the case until it was sent to a facility outside the country. Our report highlights the limitations and challenges of histology in making a definitive diagnosis of ALCL and the overt importance of immunohistochemical and cytogenetic techniques which are largely unavailable in resource-constrained environment typical of tertiary centers in Nigeria and most sub-Saharan Africa countries.

Anaplastic large cell lymphoma: Report of two cases with rare patterns (carcinomatous and sarcomatous) in fine needle aspiration cytology and histopathology

Anaplastic large cell lymphoma (ALCL) is a non-Hodgkin lymphoma of T-cell or null-cell lineage with variable cytomorphology. We report two rare ALCL cases with carcinomatous and sarcomatous patterns, respectively, in fine needle aspiration (FNA) cytology and histopathology. The first case was a 56-year-old man with enlarged left inguinal lymph node. FNA smears showed a malignant small round cell tumor with nuclear molding. In addition, there were large bi-nucleated and multinucleated cells with wreath-like arrangement of nuclei. ALCL and small cell (neuroendocrine) carcinoma were the possibilities considered. Immunocytochemical studies on FNA smears showed positive reaction for leukocyte common antigen (LCA) and negative results for cytokeratin (CK) and chromogranin. Histopathological examination of the lymph node showed features of ALCL with following immunohistochemical staining results: LCA+, CD30+, CD45RO+, CD20-, CD3+ (weak), and Alk1-. During review of sections, areas resembling a small cell anaplastic carcinoma were observed. The second case was a 24-year-old woman with right cervical lymphadenopathy. FNA smears showed an ALCL with highly atypical large cells including bi-nucleated and donut shaped cells, which were positive for CD30, EMA, and Alk-1 protein, and negative for CD20, CD3, and CK. Histopathological examination corroborated the cytodiagnosis of ALCL, and with positive immunohistochemical staining for CD30, EMA, Alk-1 protein+, BCL6+, and Ki67+ (40% cells) and negative results for CD20, CD10, CD3, CD5, CD15, BCl2, CD79a, and CD68. Sarcomatous components were noticed during review of cytologic and histopathological specimen. Awareness about these unusual cytomorphological patterns in ALCL may be of help in proper diagnosis of this neoplasm.

A Proposal for the Performance, Classification, and Reporting of Lymph Node Fine-Needle Aspiration Cytopathology: The Sydney System

BACKGROUND

The evaluation of lymph nodes (LN) by fine-needle aspiration cytology (FNAC) is routinely used in many institutions but it is not uniformly accepted mainly because of the lack of guidelines and a cytopathological diagnostic classification. A committee of cytopathologists has developed a system of performance, classification, and reporting for LN-FNAC.

METHODS

The committee members prepared a document that has circulated among them five times; the final text has been approved by all the participants. It is based on a review of the international literature and on the expertise of the members. The system integrates clinical and imaging data with cytopathological features and ancillary techniques. The project has received the endorsement and patronage of the International Academy of Cytology and the European Federation of the Cytology Societies.

RESULTS

Clinical, imaging, and serological data of lymphadenopathies, indications for LN-FNAC, technical procedures, and ancillary techniques are evaluated with specific recommendations. The reporting system includes two diagnostic levels. The first should provide basic diagnostic information and includes five categories: inadequate/insufficient, benign, atypical lymphoid cells of undetermined/uncertain significance, suspicious, and malignant. For each category, specific recommendations are provided. The second diagnostic level, when achievable, should produce the identification of specific benign or malignant entities and additional information by utilizing ancillary testing.

CONCLUSION

The authors believe that the introduction of this system for performing and reporting LN-FNAC may improve the quality of the procedure, the report, and the communication between cytopathologists and the clinicians. This system may lead to a greater acceptance and utilization of LN-FNAC and to a better interdisciplinary understanding of the results of this procedure.

Anaplastic Lymphoma Kinase Immunocytochemistry in Fine Needle Aspiration Diagnosis of Anaplastic Large-cell Lymphoma

Background:

Anaplastic large-cell lymphoma (ALCL) is a rare subtype of non-Hodgkin's lymphoma (NHL) characterized by the presence of unusual giant cells. It is a CD30+lymphoma of T-cells lineage, which shows anaplastic lymphoma kinase-nucleophosmin (ALK-NPM) rearrangement. ALCL on fine needle aspiration cytology (FNAC) shows unusually large and bizarre tumor cells.

Materials and Methods:

All aspirates seen over a 6-year period from November 2009 to November 2015 in which a diagnosis of ALCL or Hodgkin's lymphoma (HL) with bizarre giant cells were suspected on cytomorphology were prospectively selected. Twenty such aspirates were subjected to CD-30 and ALK-1 immunocytochemistry (ICC). Subsequent biopsy was available in all cases.

Results:

Out of 20 cases, seven cases, suspected to be ALCL on FNAC, were confirmed on biopsy. ALK-1 was positive in both cytology and biopsy of 6/7 of these. Two cases suspected to be ALCL on cytomorphology were HL (1) and diffuse large B-cell lymphoma (DLBCL) (1) on biopsy, both of which were ALK-1 negative on cytology. Eight cases of HL and three cases of large-cell NHL, which were all ALK negative on cytology, were confirmed on biopsy.

Conclusion:

ICC for ALK and CD30 is useful in aspiration cytodiagnosis of ALCL. One CD30 positive DLBCL and one ALK negative ALCL showed concordant results of ICC on cytology and histology.

Contribution of Immunocytochemistry to the Diagnosis of Usual and Unusual Lymphoma Cases

Some of the limitations of fine needle aspiration (FNA) in the cytodiagnosis of lymphoma include problems encountered in differentiating reactive hyperplasia from low-grade non-Hodgkin lymphoma (NHL), lower cytodiagnostic accuracy for NHL with a follicular (nodular) pattern and nodular sclerosis type of classical Hodgkin lymphoma (HL), and overlapping morphological features between T-cell-rich B-cell lymphoma (TCRBCL), anaplastic large cell lymphoma (ALCL), and HL. Immunocytochemistry may be of help in such situations. The B-cell lymphomas such as small lymphocytic lymphoma/CLL, follicular lymphoma (FL), mantle cell lymphoma (MCL), MALT lymphoma, Burkitt lymphoma (BL), and diffuse large B-cell lymphoma (DLBCL) have pan-B-cell markers (CD19, CD20, CD22, CD23, and CD79a). The FL (centrocytic), MCL, and MALT lymphoma can be differentiated with the use of a panel consisting of CD5, CD10, and CD23. In addition, FL is BCL2+ and MCL is BCL2+ as well as cyclin D1+. The DLBCL is BCL6+ in 60–90% cases. Besides pan B-cell marker, the immunocytochemical profile of BL includes CD10+, BCl6+, EBV±, and Ki67+ (100% cells). TCRBCL, a rare variant of DLBCL can be immunocytochemically differentiated from anaplastic large cell lymphoma (CD45+, CD30+, CD15‒, T±, B‒, EMA+, ALK1±) and classical HL (CD30+, CD15+, CD45‒, B‒, T‒, EMA‒). Unlike classical HL, the nodular lymphocytic predominant HL has a phenotype that includes LCA+, CD20+, CD79a+, CD15‒, and CD30‒. Whereas the immature neoplastic cells of T-lymphoblastic lymphoma (LBL) are CD3+, CD20‒, and Tdt+, the rarely encountered mature T-CLL/T-PLL are immunophenotypically CD3+, CD4+, CD5+, CD7+, CD8‒, CD20‒, CD23‒, and Tdt‒.

Anaplastic large cell lymphoma: A great mimic on cytology

Anaplastic large cell lymphoma (ALCL) is a T-cell lymphoma, accounting for <5% of non-Hodgkin's lymphoma. Cutaneous involvement can be primary or secondary arising in systemic ALCL. The diagnostic feature in both is the presence of pleomorphic, CD30 positive hallmark cells. We present a case of ALCL in a 19-year-old male presenting as an ulcerated scalp swelling. Clinical impression was actinomycosis or scrofuloderma. Cytology smears showed large dispersed pleomorphic cells with hyperlobated nuclei and multinucleated giant cells. The differentials considered were ALCL, rhabdomyosarcoma, and poorly differentiated carcinoma. Immunocytochemistry (ICC) showed positivity for leukocyte common antigen (LCA) and CD30 while negativity for desmin, favoring ALCL. Computed tomography (CT) showed a lytic paravertebral lesion. Subsequently, both paraspinal and scalp lesions were biopsied and immunochemistry confirmed the diagnosis of ALCL. Thus, cutaneous involvement in ALCL can resemble inflammatory and other neoplastic lesions clinically and cytologically. Hence, a high index of suspicion and ICC can aid in the correct diagnosis on fine needle aspiration cytology (FNAC).

Cytopathologic features of epithelioid inflammatory myofibroblastic sarcoma with correlation of histopathology, immunohistochemistry, and molecular cytogenetic analysis

BACKGROUND

Epithelioid inflammatory myofibroblastic sarcoma (E-IMS) is a recently established rare variant of inflammatory myofibroblastic tumor. It is characterized by a distinctive constellation of clinical, pathological, and molecular features, including a nearly exclusive intraabdominal location, strong male predilection, aggressive clinical course, predominance of epithelioid tumor cells, and Ran-binding protein 2 (RANBP2)-anaplastic lymphoma kinase (ALK) fusion in the majority of cases. To the authors' knowledge, the cytologic features of E-IMS have not been described to date.

METHODS

Cases of E-IMS that had corresponding cytology were searched. Six cytology samples (1 fine-needle aspiration sample, 2 imprint samples, and 3 effusion fluids) containing tumor cells were identified in 5 patients with E-IMS.

RESULTS

The cytomorphology included large monotonous epithelioid cells arranged in loose aggregates or singly, with admixed myxoid stroma, and an inflammatory background rich in neutrophils. The tumor cells had a large, round, eccentric nucleus with vesicular chromatin, prominent nucleoli, and moderate amounts of pale cytoplasm. Delicate thin-walled branching vessels traversing tumor aggregates was a prominent feature in a fine-needle aspiration sample. Immunohistochemically, ALK was positive in all 5 tumors, with a nuclear membranous staining pattern noted in 3 cases and a cytoplasmic pattern observed in the other 2 cases. ALK rearrangement was confirmed in all 5 tumors by molecular genetic studies.

CONCLUSIONS

The cytologic features of E-IMS recapitulate its histologic characteristics. E-IMS merits inclusion in the differential diagnosis of any intraabdominal, large epithelioid cell neoplasm. Confirmation of ALK rearrangement is advisable because patients may benefit from targeted therapies.

Flow cytometric immunophenotyping and cell block immunocytochemistry in the diagnosis of primary Non-Hodgkin's Lymphoma by fine-needle aspiration: Experience from a tertiary care center

Background:

Accurate diagnosis of Non-Hodgkin's Lymphoma (NHL) on fine-needle aspiration (FNA) specimen is challenging and requires ancillary testing.

Aim:

The feasibility of flow cytometric immunophenotyping (FCI) along with cell block immunocytochemistry (CB-ICC) as adjunct techniques in the diagnosis of NHL as per the current World Health Organization (WHO) classification was evaluated.

Materials and Methods:

All cases of suspected lymphoma underwent FNA, and the sample was triaged for light microscopic evaluation, FCI, and CB-ICC, and each case was classified as per the current WHO classification.

Results:

A total of 65 cases was analyzed which included 40 B-cell, 21 T-cell, and 4 unclassifiable lymphomas. Of 61 cases, FCI alone was contributory in 74% (45/61) cases whereas CB-ICC alone was contributory in 65.5% (40/61) cases in typing the lymphoma. In 11.4% (7/61) cases, the lymphoma could not be classified by either technique. Thus, in a total of 88.5% (54/61) cases a combination of FCI and CB-ICC from FNA enabled a diagnosis of lymphoma with its subtyping.

Conclusion:

Flow cytometric immunophenotyping and ICC on CBs are feasible on FNA material and are very useful in a suspected case of NHL especially when a biopsy may not be possible or feasible.

Extranodal anaplastic large cell lymphoma mimicking sarcoma: A report of an interesting case

Lymphomas are malignancies of the lymphoid tissues involving cells of the immune system. Primary systemic anaplastic large cell lymphoma (ALCL) represents an aggressive lymphoma characterized by neoplastic proliferation of lymphoid cells with an anaplastic appearance. Large pleomorphic cells are “hallmark” cells with horseshoe-shaped or kidney-shaped nuclei and a constant expression of the CD30 molecule on all neoplastic cells. There is a vast morphological spectrum posing a challenge to pathologists in the diagnosis of ALCL.

Imprint cytology facilitating the diagnosis of primary cutaneous anaplastic large cell lymphoma of iliac fossa

Primary cutaneous anaplastic large cell lymphoma (C-ALCL) is a form of cutaneous T-cell lymphoma that is characterized by solitary nodules and plaques. In this report, the authors present an unusual case of a 59-year-old male with a solitary ulcerofungative mass in the left iliac fossa clinically masquerading as sqaumous cell carcinoma. The imprint smears of the lesion had characterstic morphological features which helped in the diagnosis. Subsequently, the imprint cytology correlated well with the histopathology and immunohistochemical studies highlighting its utility as simple, rapid, and easy test.

ALK-negative anaplastic large cell lymphoma mimicking a soft tissue sarcoma

Anaplastic lymphoma kinase protein (ALK)-negative anaplastic large cell lymphoma (ALCL) has a vast morphologic spectrum and may mimic many other types of malignancies both cytologically and histologically. There are only a few published case reports/series describing the cytomorphologic features of ALCL on fine-needle aspiration (FNA) biopsy specimens. We describe a case of ALK-negative ALCL mimicking a high-grade soft tissue sarcoma of the thigh in a 62-year-old man. The characteristic morphologic findings on FNA and core biopsy along with the immunophenotypic profile are described and reviewed. The diagnosis of ALCL on FNA biopsy may be difficult, but can be done successfully with the use of ancillary tests. Therefore, it must be considered in the differential diagnosis of lesions with pleomorphism, anaplasia, and wreath-like or horseshoe-shaped nuclei to ensure that adequate material is obtained for ancillary studies.

Cytomorphologic features of primary anaplastic large cell lymphoma of the psoas muscle: a case report and literature review

Ki-1 (CD30) positive anaplastic large cell lymphoma (ALCL) is an uncommon malignancy, which may present with nodal as well as extra-nodal disease. Primary skeletal muscle Ki-1 (CD30) positive ALCL is an even rarer event with few cases reported in the literature and only some with published cytomorphologic features. An 83-year-old woman underwent a fine needle aspiration (FNA) of a psoas muscle mass. Smears demonstrated a predominantly discohesive population of large pleomorphic cells. The nuclei were hypechromatic and lobulated, with often multinucleation. Nucleoli were prominent in a subset of cells. Cytoplasmic vacuolization was also present. No lymphoglandular bodies were identified. A cytodiagnosis of malignant cells favoring metastatic melanoma vs. poorly differentiated carcinoma was rendered. Morphologic and immunohistochemical features later revealed a primary psoas muscle Ki-1 (CD30) positive ALCL with negative staining for anaplastic large cell lymphoma kinase (ALK). Cytologic features of ALCL mimic epithelial neoplasms, sarcomas, melanoma and other lymphomas. Although rare, ALCL should be a diagnostic consideration when discohesive pleomorphic malignant cells are encountered on FNA of a muscle neoplasm.

Fine needle aspiration cytology of ALK1(-), CD30+ anaplastic large cell lymphoma post renal transplantation: a case report and literature review

Post transplant lymphoproliferative disorders (PTLD) complicates the course of 0.3 to 3% of renal transplant patients receiving immunosuppression. Epstein-Barr virus (EBV) related non-Hodgkin's lymphomas of B-cell type is more common than those of T-cell origin. CD30 positive Anaplastic Large Cell Lymphoma (ALCL) is a Non-Hodgkin's lymphoma (B or T cell type) that accounts for a small percentage of PTLD's. ALCL of T-cell type are a spectrum of disease ranging from primary cutaneous to systemic nodal ALCL. The systemic nodal ALCL is further subdivided into anaplastic lymphoma kinase-1 (ALK-1) positive or negative. ALK-1 protein is a gene fusion product of translocation (2;5) and carries prognostic implications. We present an unusual manifestation of ALK-1 negative CD30 positive ALCL in a post renal transplant patient in FNA cytology with all supportive adjuvant studies and differential diagnoses and review the cytology literature on this topic.