Langerhans cell sarcoma with lineage infidelity/plasticity: a diagnostic challenge and insight into the pathobiology of the disease.

Langerhans cell sarcoma is a very rare and aggressive tumor of Langerhans cell lineage, for which aberrant expression of T-cell-related antigens has not yet been reported in a primary skin tumor. The authors describe the first known case of a primary cutaneous Langerhans cell sarcoma with lineage infidelity and use comparative genomic hybridization to investigate the genetic composition of the tumor and detect DNA copy number alterations throughout its entire genome. The case involves a 62-year-old woman who presented with an irregular nodule on the forehead surrounded by smaller lesions in its vicinity. The clinical impression was melanoma with satellitosis. The biopsy specimen showed an epidermotropic tumor with moderate-to-marked cellular pleomorphism and significantly increased mitotic rate but no necrosis. The immunoprofile of the lesion was remarkable, as next to common Langerhans cell markers: Langerin, CD1a, S100, and CD4; it also exhibited an aberrant T-cell phenotype with the expression of CD2, CD3, and CD43. In addition, fascin and CD30 were also expressed, further exaggerating potential diagnostic pitfalls. Langerhans cell lineage was confirmed by the demonstration of characteristic Birbeck granules on electron microscopy. Whole genome analysis for copy number changes and loss of heterozygosity showed a complex karyotype with variable hyperdiploidy and numerous allelic imbalances. Significant findings included a homozygous deletion at 9p21 involving the CDKN2A and loss of heterozygosity at 17p involving TP53 gene, coupled with a TP53 missense mutation. Despite reexcision and multiagent systemic chemotherapy, the patient died of metastasis 2 years after diagnosis. This case is an outstanding example of lineage infidelity in a hematologic malignancy and the utilization of comparative genomic hybridization in characterizing its genetic abnormalities.

A case of leprosy in central Florida.

Hansen disease, also known as leprosy, is a chronic granulomatous infectious disease that is caused by Mycobacterium leprae. We report an unusual case of a 65-year-old man who presented with multiple anesthetic, annular, erythematous, scaly plaques with a raised border without any known exposures to leprosy. Histologic examination revealed a perineural lymphohistiocytic infiltrate and rare bacilli demonstrated on Fite staining. After confirmation with polymerase chain reaction (PCR) and consultation with the National Hansen's Disease Program (Baton Rouge, Louisiana), the patient was placed on a regimen of rifampicin 600 mg once monthly and dapsone 100 mg once daily for 6 months, which showed considerable improvement. This case demonstrates the identification of leprosy in central Florida, a region that is not known to be endemic to the disease. Leprosy, however rare, must be part of a practitioner's differential diagnosis even without history of traditional exposures.