[Pigmented Paget's disease of the breast]. / Maladie de Paget mammaire pigmentée.

INTRODUCTION: Pigmented Paget's disease of the breast is an uncommon disease. Histology shows intraepidermal pagetoid cells positive for cytokeratin7. We report a difficult case with an atypical clinic presentation as a pigmented lesion and unusual immunohistochemical results such as absence of expression of cytokeratin7 (CK7). OBSERVATION: A 68-year-old woman presented a heterogeneous pigmented lesion on the left nipple extending to the areola, over a period of six years. Histologic study of biopsy showed intraepidermal proliferation of atypical cells positive for melanocytic markers but negative for CK7. The clinicopathological features were consistent with malignant lentigo. Nevertheless, histological study of the whole lesion after complete surgical excision was in favour of mammary Paget's disease, while CK7 remained negative. DISCUSSION: Pigmented Paget's disease of the breast is infrequent, with only a few cases reported in the literature and is suggestive of malignant melanoma or pigmented metastasis of mammary adenocarcinoma. Immunohistochemistry is necessary, especially using CK7 staining, which is usually positive (sensitivity of almost 100%), except in some rare cases such as ours. In these difficult cases, study of a wider panel of antibodies may be necessary for diagnosis.

A case of primary cutaneous nasal type NK/T-cell lymphoma and review of the literature.

INTRODUCTION: Cutaneous T-cell lymphoma subtypes are now better identified thanks to progress in immunohistochemistry. This article describes a new case of primary cutaneous natural killer/T-cell lymphoma of nasal type (NKTL-NT) and reviews 18 other cases of this rare neoplasm. CASE REPORT: A 79-year-old man presented with a 3-cm nodular tumor of the left leg occurring on a primary chronic lymphedema of the legs. The lesion was CD56+, CD3 intracytoplasmic+, CD45+ and Epstein-Barr virus+. A comprehensive workup including CT scan and bone marrow biopsy was negative and a diagnosis of NKTL-NT with a primary cutaneous involvement was made. The patient was free of disease under multi-agent chemotherapy after 24 months of follow-up. DISCUSSION: After reviewing 18 other cases of primary cutaneous NKTL-NT, we conclude that the prognosis of these lymphomas is usually poor. However, limited cutaneous forms have a longer median survival than extracutaneous variants.