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This case report describes an unusually large facial pilomatrix carcinoma (PC) in a 60-year-old man. This PC had been growing slowly for 11 months and had recently ulcerated. It measured 9 cm × 7 cm × 5 cm. Initial punch biopsy findings were inconclusive. The tumor was excised in total with 5-mm margins in a supra-superficial musculoaponeurotic system plane. The defect was reconstructed with a cervicofacial bilobed rotational advancement flap. Histopathologic findings confirmed the diagnosis of PC. There was no lymph node spread or distant metastasis. The patient recovered with a good esthetic result. This case represents one of the largest facial PCs reported in the literature. Diagnostic challenges are discussed, and the literature is reviewed., (Copyright © 2017 American Association of Oral and Maxillofacial Surgeons. Published by Elsevier Inc. All rights reserved.)

The atypical cellular blue nevus is an extremely rare nevomelanocytic lesion which lacks precise histologic characterization in the current literature. Given the potential for significant architectural and cytologic overlap with melanoma, further study, including molecular analysis, is needed. This is the first description of an atypical cellular blue nevus of the oral cavity.

Background: Rituximab has been used to treat relapsed low-grade or advanced non-Hodgkin's lymphoma since 1997, targeting the CD20 antigen expressed by B cells. Single-agent rituximab therapy is safe and well tolerated. Recurrences showing a loss of CD20 expression following rituximab therapy have been reported., Methods: Four patients with CD20-positive cutaneous B-cell lymphoma received rituximab therapy with subsequent recurrences. The biopsies were assessed for cytoplasmic CD20 expression; CD20 messenger RNA was also assessed where tissue was available., Results: Cutaneous relapses occurring within 1.5-3 months following the last dose of rituximab were CD20 negative. In three cases, subsequent relapses showed renewed expression of CD20. Those biopsies demonstrating a loss of surface and cytoplasmic CD20 by immunohistochemistry also showed no evidence of messenger RNA for CD20 using an in situ polymerase chain reaction-based methodology., Conclusions: Rituximab may be associated with the emergence of CD20-negative B-cell clones, potentially rendering a tumor insensitive to this drug. Conversely, following cessation of the drug, a re-expression of CD20 within the neoplastic cells may occur allowing therapeutic intervention with this monoclonal antibody. The loss of CD20 expression appears to be a direct effect of the drug on CD20 messenger RNA synthesis.