title: Primary cutaneous folliculotropic and lymphohistiocytic anaplastic large cell lymphoma.
abstract: BACKGROUND
  Primary cutaneous anaplastic large cell lymphoma (PC-ALCL) is a T-cell lymphoma that presents in the skin and consists of CD30+ anaplastic large lymphocytes with abundant cytoplasm and pleomorphic nuclei. In addition to the classic variant, several other histologic patterns of ALCL have been identified, among them the lymphohistiocytic variant.
  
  
  OBJECTIVE
  We describe a case of the lymphohistiocytic variant of PC-ALCL with a marked follicular involvement. The lesion appeared as a single nodule in the face that completely regressed following biopsy. A diffuse infiltration of lymphocytes and macrophages was seen in the dermis associated with hypertrophied hair follicles, follicular mucinosis, and marked folliculotropism, leading to follicular disruption. Cohesive groups of CD30+ large, atypical lymphocytes with a high proliferative index were seen focally. The patient was followed up for 41 months, during which time no relapses occurred.
  
  
  CONCLUSIONS
  This case shows that PC-ALCL may present with different histologic features, including a follicular variant, that may mimic both benign and malignant conditions.
authors.affiliation: Department of Pathology, Federal University of Bahia, Salvador, Bahia, Brazil. achilea@uol.com.br
authors.forename: Achiléa L
authors.initials: AL
authors.lastname: Bittencourt
authors.forename: Rodrigo Ferreira
authors.initials: RF
authors.lastname: de Oliveira
authors.forename: Jussamara Brito
authors.initials: JB
authors.lastname: Santos
mesh_terms: D001706:Biopsy; D003937:Diagnosis, Differential; D006801:Humans; D007150:Immunohistochemistry; D054446:Lymphoma, Primary Cutaneous Anaplastic Large Cell / Q000175:diagnosis* / Q000473:pathology; D008297:Male; D008875:Middle Aged; D012878:Skin Neoplasms / Q000175:diagnosis* / Q000473:pathology