A small cell variant of ALK-positive, CD8-positive anaplastic large cell lymphoma with primary subcutaneous presentation mimicking subcutaneous panniculitis-like T-cell lymphoma

Small cell variant of ALK-positive anaplastic large cell lymphoma with primary subcutaneous presentation: A case report

RATIONALE

The rare morphological variant of anaplastic large cell lymphoma (ALCL) may pose a challenge in diagnosis, especially when presentation primarily involves skin lesions.

PATIENT CONCERNS

Here we describe a rare case of small cell variant of ALCL in an 11-year-old girl.

DIAGNOSIS

We performed clinical, morphological, and immunohistochemical analyses of developed cutaneous nodules.

INTERVENTIONS

Pathologists should consider this small cell variant in ALCL differential diagnosis, as early and correct diagnosis has important clinical implications.

OUTCOMES

Allogeneic hematopoietic stem cell transplantation appears to be a promising treatment option for small cell variant of ALCL.

LESSONS

Histological diagnosis of small cell variant of ALCL is challenging among pediatricians because of its low incidence and atypical presentation. We provide a short review of the small cell variant of ALCL to facilitate the diagnosis of this difficult-to-recognize entity.

Expression of CD8 is associated with non-common type morphology and outcome in pediatric anaplastic lymphoma kinase-positive anaplastic large cell lymphoma

Anaplastic lymphoma kinase-positive anaplastic large T-cell lymphoma is characterized by morphological variability. Morphological variants (non-common subtype) are associated with a poor outcome. They display abundant reactive bystander cells admixed with the lymphoma cells. So far, the difficulty in distinguishing lymphoma cells from bystander cells by visual inspection has prevented detailed and reliable immunophenotypic analysis using conventional immunohistochemistry. To overcome these limitations, we analyzed 124 cases of pediatric anaplastic lymphoma kinase-positive anaplastic large cell lymphoma treated within clinical trials using immunofluorescence multi-staining and digital image analysis combining antibodies against anaplastic lymphoma kinase to specifically identify lymphoma cells with antibodies against CD30, CD3, CD5, CD8, Ki67 and phosphorylated STAT3. Non-common type anaplastic lymphoma kinase-positive anaplastic large cell lymphomas express CD8 more frequently than common type anaplastic lymphoma kinase-positive anaplastic large cell lymphomas (35.4% and 5.6%, respectively; P=0.0002). CD8 expression was associated with a poorer outcome. Importantly, in a multivariate analysis including clinical risk factors, histological subtype and CD8 expression, CD8-positivity proved to be an independent prognostic predictor of worse outcome (hazard ratio for survival 3.38, P=0.042).

Anaplastic lymphoma kinase (ALK1) immunohistochemistry in diagnostic dermatopathology; an update

The use of anaplastic lymphoma kinase antibodies (ALK1) as a diagnostic aid has expanded since becoming a routinely available immunohistochemical stain. Because the skin may be the site of a wide variety of hematolymphoid and fibroblastic proliferations, dermatopathologists commonly use ALK1 as part of a broader staining panel in diagnosing soft tissue and cutaneous hematolymphoid neoplasms. Furthermore, new entities and differential diagnostic contexts are emerging, which broaden the utility of ALK1 immunohistochemistry. We review the expanding role of ALK1 immunohistochemistry in contemporary dermatopathology.