Histopathological aspects of cutaneous lymphoma

A review of Merkel cell carcinoma

ABSTRACT

Merkel cell carcinoma (MCC) is a rare and aggressive type of metastatic, nonmelanoma skin cancer derived from Merkel cells in the epidermis. MCC can be induced by sun exposure or via Merkel cell polyomavirus (MCV) gene expression. MCV is found in most patients with MCC and is associated with a lower recurrence rate of MCC. MCC has a wide range of clinical presentations that make diagnosis challenging. Histologic examination is performed using unique markers to differentiate it from other diagnoses. This article reviews the pathogenesis, clinical presentation, histopathology, differential diagnosis, and treatment of MCC.

[The history of lymphoma classifications with special consideration of cutaneous lymphomas]

For modern evidence-based medicine, classification systems are necessary to guarantee a uniform approach for therapy and for estimating prognosis. The comparability of clinical studies and international communication require a common language and are only possible with modern international classification systems. But because all classifications are artificial, they only mirror the current state of knowledge and may change dramatically over decades. This review discusses the history of lymphoma classifications systems with a special focus on the topic of primary cutaneous lymphomas, emphasizing special problems in terminology.

[Dilemmas associated with the surgical treatment of cutaneous B cell lymphomas]

INTRODUCTION

Cutaneous lymphomas belong to the group of non-Hodgkin lymphomas. However, in case of an in-time diagnose and adequate treatment the prognosis of the disease is fairly good. Nevertheless, a thorny path leads to the correct diagnosis as several dermatological diseases cause problems in differential diagnostics.

CASE REPORT

The authors describe the case history of a 53-year-old woman patient, who had a dermatological check-up due to a dermatitis in the shoulder region. A conservative treatment was started because of a suspected mycosis. Following its inefficiency an operative excision was carried out. The postoperative biopsy verified cutaneous B-cell lymphoma.

DISCUSSION

The cutaneous B-cell lymphomas are such forms of non-Hodgkin lymphomas, where the malignant proliferation appears primarily in the skin, and in 6 months after the diagnosis extracutaneous manifestation cannot be detected. Several cases can be found in the literature, which show long interval between the manifestation of the symptoms and the setting of the diagnosis. This calls the attention to the significance of difficulties in the differential diagnosis. During the treatment of cutaneous lymphomas the type, the cutaneous extension, and the extracutaneous manifestation of the disease must be defined. The therapeutic plan can be made up by analysing these findings. On the basis of findings in this case and in the literature, a surgical treatment--beyond determining the correct diagnosis--could be a therapeutic alternative in the treatment of cutaneous B-cell lymphomas.

The new World Health Organization classification of haematopoietic and lymphoid tumours: a dermatopathological perspective

The World Health Organization (WHO) has published a new consensus classification of tumours of haematopoietic and lymphoid tissue, based on recognizable disease entities defined by clinical and scientific criteria. The WHO does not support the use of stand-alone organ-related classifications, such as for skin. The Royal College of Pathologists (London) has adopted the WHO classification in its minimum dataset for the histopathological reporting of lymphoma and this will be used in the National Health Service Skin Cancer Dataset. The purpose of this review is to highlight the principal primary and secondary cutaneous haematopoietic and lymphoid tumours that are defined in the WHO classification. The review also discusses selected problematical areas in the WHO classification relevant to the skin and contains suggestions to encourage a unified approach in the use of the WHO coded summary. These represent an attempt to facilitate future progress and research in the field of cutaneous lymphoma. They are perceived as possible building-blocks for wider discussion and not as alterations to the classification. The WHO classification has been compared with a road map that indicates directions for future clinical and scientific research.