title: Ki-1-positive anaplastic large-cell lymphoma can mimic benign dermatoses.
abstract: BACKGROUND
  Regressing atypical histiocytosis is a recently described disease characterized by recurrent nodules or ulcers. The cutaneous lesions appear abruptly and then regress only to return in a manner reminiscent of lymphomatoid papulosis. Immunophenotypic analysis has revealed that most cases are a form of anaplastic large-cell Ki-1-positive (CD30+) lymphoma.
  
  
  OBJECTIVE
  We describe two patients with Ki-1-positive anaplastic large-cell lymphoma that had clinical and pathologic features of regressing atypical histiocytosis and mimicked benign dermatoses (pyoderma gangrenosum and morphea), causing a delay in confirming the true diagnosis. A third case that was readily recognized as a lymphoma is also presented.
  
  
  METHODS
  The clinical and histopathologic findings were recorded. In addition, T-cell receptor gene rearrangement and immunophenotyping were determined in the index case.
  
  
  RESULTS
  The index patient and second patient were diagnosed as having Ki-1-positive anaplastic large-cell lymphoma by immunophenotyping and underwent cyclophosphamide, doxorubicin, prednisone, and vincristine (CHOP) chemotherapy with complete remission. The patient detected by chart review died of her disease without receiving antineoplastic therapy; disseminated lymphoma was diagnosed at autopsy. Studies on paraffin-embedded tissue were consistent with Ki-1-positive anaplastic large-cell lymphoma.
  
  
  CONCLUSIONS
  Regressing atypical histiocytosis may clinically resemble some benign dermatoses. Recent evaluation of these cases has shown that many represent a form of Ki-1-positive anaplastic large-cell lymphoma. Multiple skin biopsy specimens with immunophenotyping and gene rearrangement studies are required to arrive at the diagnosis.
authors.affiliation: Department of Dermatology, Cleveland Clinic Foundation.
authors.forename: C
authors.initials: C
authors.lastname: Camisa
authors.forename: T N
authors.initials: TN
authors.lastname: Helm
authors.forename: C
authors.initials: C
authors.lastname: Sexton
authors.forename: R
authors.initials: R
authors.lastname: Tuthill
mesh_terms: D000328:Adult; D000368:Aged; D000971:Antineoplastic Combined Chemotherapy Protocols / Q000627:therapeutic use; D001706:Biopsy; D003520:Cyclophosphamide / Q000008:administration & dosage; D003937:Diagnosis, Differential; D003951:Diagnostic Errors; D004317:Doxorubicin / Q000008:administration & dosage; D005260:Female; D015870:Gene Expression; D015329:Gene Rearrangement, T-Lymphocyte; D006801:Humans; D016130:Immunophenotyping; D017730:Ki-1 Antigen / Q000032:analysis; D017728:Lymphoma, Large-Cell, Anaplastic / Q000175:diagnosis* / Q000188:drug therapy / Q000276:immunology; D008297:Male; D008875:Middle Aged; D011241:Prednisone / Q000008:administration & dosage; D017511:Pyoderma Gangrenosum / Q000175:diagnosis*; D012594:Scleroderma, Localized / Q000175:diagnosis*; D012867:Skin / Q000473:pathology*; D013997:Time Factors; D014750:Vincristine / Q000008:administration & dosage
chemical_list: D017730:Ki-1 Antigen; D014750:Vincristine; D004317:Doxorubicin; D003520:Cyclophosphamide; D011241:Prednisone