Pseudocarcinomatous Hyperplasia Masquerading as a Well-Differentiated Squamous Cell Carcinoma Associated With Primary Cutaneous Anaplastic Large-Cell Lymphoma

ABSTRACT

Pseudocarcinomatous hyperplasia (PCH) is a reactive proliferation of the epidermis associated with CD30 + lymphoproliferative disorders. In this article, we report the case of a 42-year-old man who presented with a 10-year history of a solitary erythematous patch on the right thigh that progressed to an ulcerated, crusted plaque. Histologic examination revealed an infiltrate of atypical CD30 + lymphocytes consistent with primary cutaneous anaplastic large-cell lymphoma with overlying well differentiated keratinocyte hyperplasia akin to a well-differentiated invasive squamous cell carcinoma. This case demonstrates the phenomenon of pseudocarcinomatous hyperplasia mimicking features of invasive squamous cell carcinoma. It highlights the necessity of careful clinical correlation when diagnosing squamous cell carcinomas in younger patients on non-sun-exposed areas and the exclusion of accompanying known causes of pseudocarcinomatous hyperplasia.

Pseudocarcinomatous Hyperplasia, Squamous Cell Carcinoma, and Keratoacanthoma Associated to Lymphomas of the Skin and External Mucous Membranes: A Case Report and Literature Review

Pseudocarcinomatous hyperplasia (PCH) is a benign reactive epithelial proliferation that may be associated to lymphomas of the skin or external mucous membranes. We present a case of single lesion mycosis fungoides (Woringer-Kollop's reticulosis pagetoid) associated with PCH that was initially misdiagnosed as squamous cell carcinoma (SCC) and review all PubMed-indexed previously reported cases on lymphomas of the skin or external mucous membranes associated to PCH, SCC, and keratoacanthomas. Including our own case, we collected data of 114 cases of cutaneous or mucosal lymphoproliferative disorders associated to PCH, 3 cases associated to SCC, and other 3 cases associated to keratoacanthomas. All cases were tabulated to the following parameters whenever data was available: sex, age, previous medical conditions, number of lesions (single × multiple), site of involvement (mucosa, skin or both), clinical impression, initial equivocal histopathologic diagnosis, final diagnosis, keratinocytic atypia (presence × absence), lymphocytic atypia (presence × absence), CD30-status, and treatment.

Lymphomatoid papulosis: an update and review

Lymphomatoid papulosis (LyP) is a benign chronic often relapsing skin condition that belongs to the CD30-positive cutaneous lymphoproliferative disorders. LyP typically presents as crops of lesions with a tendency to self-resolve, and morphology can range from solitary to agminated or diffuse papules and plaques to nodules or tumours. The clinical-histological spectrum can range from borderline cases to overlap with primary cutaneous anaplastic cell lymphoma (pcALCL). Histology and immunophenotype commonly show overlap with other CD30-positive disorders and sometimes may be identical to pcALCL, making its diagnosis more difficult. Patients with LyP have an increased risk of developing a second neoplasm such as mycosis fungoides, pcALCL and/or Hodgkin lymphoma. Clinical correlation allows its proper classification and diagnosis, which is fundamental for treatment and prognosis. This review focuses on the clinical appearance, histopathological features, diagnosis, differential diagnosis and management of LyP.

A new era for cutaneous CD30-positive T-cell lymphoproliferative disorders

Cutaneous CD30+ T-cell lymphoproliferative disorders (CD30+ T-LPD) represent a spectrum encompassing lymphomatoid papulosis (LyP), primary cutaneous anaplastic large-cell lymphoma (pcALCL) and borderline lesions. They share the expression of CD30 as a common phenotypic marker. They differ however in their clinical presentation, the histological features and clinical course. Moreover, LyP and PcALCL show numerous clinical, histological and phenotypic variants. Overlapping features of LyP and pcALCL with themselves and with other cutaneous and systemic lymphomas emphasize the importance of careful clinicopathologic correlation and staging in the diagnosis of CD30+ T-LPD. Furthermore, an increasing number of inflammatory and infectious skin disorders harboring medium-sized to large CD30+ cells have to be considered in the differential diagnosis. Whereas the expression of CD30 in cutaneous CD30+ T-LPD stands for a favourable prognosis, its expression in other cutaneous and systemic lymphomas has a divergent impact. The assessment of CD30 expression does not only provide prognostic information, but is of potential therapeutic relevance as CD30 can serve as a therapeutic target. This review focuses on the clinicopathological and phenotypic spectrum of CD30+ T-LPD, its differential diagnoses and the role of CD30 as a diagnostic, prognostic and therapeutic marker.