Childhood mycosis fungoides with a CD8+ CD56+ cytotoxic immunophenotype

A Comprehensive Update of the Atypical, Rare and Mimicking Presentations of Mycosis Fungoides

Introduction

Mycosis fungoides (MF) is the most frequent subtype of primary cutaneous T cell lymphomas (pCTCL). The diagnosis may be particularly difficult in the early stages as well as in atypical and rare clinical presentations. Furthermore, MF may simulate a large variety of common dermatologic disorders and patterns, both histopathologically and clinically.

Methods

A literature search was performed to provide a comprehensive update on the rare and atypical MF manifestations as well as the dermatoses and dermatological patterns that could be imitated by MF.

Results

A total of 114 publications were found describing a series of different dermatoses and dermatological patterns mimicked by MF, as well as some particular localizations of MF lesions and dermatoses that occur in preexisting MF lesions.

Conclusions

The number of dermatoses that can be imitated by MF is ever-increasing. Patients with common dermatologic conditions that prove to be treatment refractory should be biopsied without delay, and sequentially as necessary, to prevent delay in diagnosis and progression of disease. Clinicopathologic correlation is the best way of diagnosis.

Cutaneous Lymphoproliferative Disorders: What's New in the Revised 4th Edition of the World Health Organization (WHO) Classification of Lymphoid Neoplasms

Cutaneous lymphoproliferative disorders remain a challenging aspect of dermatopathology, in part due to the rarity of the entities and extreme variability in clinical outcomes. Although many of the entities remain unchanged, the approach to some of them has changed in the new 2016 classification scheme of the World Health Organization. Chief among these are Epstein-Barr virus-associated lymphoproliferative disorders such as Epstein-Barr virus-associated mucocutaneous ulcer and hydroa vacciniforme-like lymphoproliferative disorder, primary cutaneous CD8+ aggressive epidermotropic cytotoxic T-cell lymphoma, primary cutaneous acral CD8+ T-cell lymphoma, primary cutaneous CD4+ small/medium T-cell lymphoproliferative disorder, and breast implant-associated anaplastic large cell lymphoma. In addition, translocations and gene rearrangements such as those involving the 6p25.3 locus have started to inform diagnosis and classification of anaplastic large cell lymphoma and lymphomatoid papulosis. In this review, we will examine what is new in the diagnostic toolbox of cutaneous lymphoproliferative disorders.

Cutaneous Hematolymphoid and Histiocytic Proliferations in Children

This article focuses on cutaneous hematopoietic neoplasms that are more likely to be encountered in the pediatric age-group and includes both lymphoproliferative and histiocytic disorders. The cutaneous hematologic disorders in children have a different epidemiologic profile to what is seen during adulthood. Although mycosis fungoides is the most frequent form of cutaneous lymphoma in adults, it is very rare in children. Because lymphoblastic leukemias and lymphomas are more frequent in the pediatric setting, cutaneous leukemic infiltrates are relatively common in this age-group. Similarly, histiocytic disorders are more common in children, particularly Langerhans cell histiocytosis and juvenile xanthogranuloma. Notably, the histiocytic disorders have undergone significant modifications on their nomenclature in the basis of the molecular characteristics that are present in them. A summary of the most frequent cutaneous hematopoietic disorders in children will be discussed further in this review.

Cutaneous T-cell Lymphoma

Cutaneous T-cell lymphomas comprise a heterogeneous group of diseases characterized by monoclonal proliferations of T lymphocytes primarily involving skin, modified skin appendages, and some mucosal sites. This article addresses the basic clinical, histologic, and immunohistochemical characteristics of this group of diseases, with additional attention to evolving literature on dermoscopy, reflectance confocal microscopy, flow cytometry, and molecular data that may increasingly be applied to diagnostic and therapeutic algorithms in these diseases. Select unusual phenotypes or diagnostic examples of classic phenotypes are demonstrated, and flags for consideration while making a pathologic diagnosis of cutaneous T-cell lymphoma are suggested.

Clinical Outcome and Prognosis of Young Patients with Mycosis Fungoides

BACKGROUND/OBJECTIVES

Mycosis fungoides (MF) in young patients is rare and may have atypical presentations. There are limited data in these patients. The objective was to determine the clinical outcome and prognosis of young patients with MF.

METHODS

A search of our institutional cancer registry database was conducted for patients diagnosed with MF at younger than 30 years of age.

RESULTS

Our study included 74 patients (median age at diagnosis 25.5 yrs). Sixty-five (88%) presented with early stage disease and variants of MF (n = 44 [59%]), leading to a median delay in diagnosis of 2.5 years. Hypopigmented MF (n = 27 [36.5%]) was the most common variant, affecting predominantly African American (44.4% vs 19%; p = 0.02) and younger (20 vs 26 yrs; p < 0.001) patients. All patients with hypopigmented MF presented with early stage disease and were less likely to develop progressive disease (PD) than those with other variants (11% vs 34%; p = 0.03). Nineteen patients (26%) developed PD during a median follow-up of 3.5 years, which was associated with advanced-stage disease (89% vs 17%; p < 0.001), older age (>20 yrs) (31% vs 13%; p = 0.08), African American race (52.6% vs 20%; p = 0.009), and poikilodermatous presentation (p < 0.01). Overall survival was good (97.2% at 5 yrs, 95.9% at 10 yrs) despite the delay in diagnosis and atypical presentation.

CONCLUSIONS

Progressive disease is associated with older age, African American race, the poikilodermatous variant, and advanced-stage disease. The hypopigmented variant is a common presentation in young patients and has an indolent disease course. Our study confirms an overall favorable prognosis in young patients with MF.

Cutaneous EBV-related lymphoproliferative disorders

This article will focus on the cutaneous lymphoproliferative disorders associated with EBV, with an emphasis on the upcoming changes in the revised 4th Edition of the WHO classification of tumors of the hematopoietic system, many of which deal with cutaneous disorders derived from NK-cells or T-cells. Extranodal NK/T-cell lymphoma usually presents in the upper aerodigestive tract, but can involve the skin secondarily. EBV-associated T- and NK-cell lymphoproliferative disorders (LPD) in the pediatric age group include the systemic diseases, chronic active EBV infection (CAEBV) and systemic EBV+ T-cell lymphoma of childhood. Hydroa vacciniforme (HV)-like LPD is a primarily cutaneous form of CAEBV and encompasses the lesions previously referred to as HV and HV-like lymphoma (HVLL). All the T/NK-cell-EBV-associated diseases occur with higher frequency in Asians, and indigenous populations from Central and South America and Mexico. Among the B-cell EBV-associated LPD two major changes have been introduced in the WHO. The previously designated EBV-positive diffuse large B-cell lymphoma (EBV-DLBCL) of the elderly, has been changed to EBV-DLBCL with 'not otherwise specified' as a modifier (NOS). A new addition to the WHO system is the more recently identified EBV+ mucocutaneous ulcer, which involves skin and mucosal-associated sites.

Unusual variants of mycosis fungoides

Conventional presentations of mycosis fungoides may be diagnostically challenging, particularly in light of the controversial boundaries defining the disease. Variant presentations of this cutaneous T-cell lymphoma add a further layer of complexity, requiring a sophisticated and informed perspective when evaluating lymphoid infiltrates in the skin. Herein we discuss well-defined (WHO-EORTC) variants pagetoid reticulosis, granulomatous slack skin and folliculotropic mycosis fungoides as well as less well-defined morphologic/architectural variants, and divergent immunohistochemical presentations of this typically indolent T-cell lymphoproliferative disease.