The expression patterns of (A) FXIIIa and (B) LSP1 were different in the same specimen of dermatofibroma

The expression patterns of (A) FXIIIa and (B) LSP1 were different in the same specimen of dermatofibroma. patterns of the three markers in individual tumors. In contrast, only 2 of 20 cases of DFSP expressed LSP1, and none of DFSP cases stained positive for FXIIIa. Conclusion The LSP1-positive cells in DF could potentially be fibrocyte-like cells. FXIIIa and CD68 expression suggests that dermal dendritic cells and histiocytes are constituent cells of DF. It is known that fibrocytes, dermal dendritic cells and histiocytes are all derived from CD14+ monocytes. Therefore, we suggest that DF may originate from CD14+ monocytes. Additionally, the LSP1 immunohistochemical stain could be useful in distinguishing between DF and DFSP. strong class=”kwd-title” Keywords: Dermatofibroma, Dermatofibrosarcoma, Leukocyte-specific protein 1 INTRODUCTION Dermatofibroma (DF) is a common skin tumor, predominantly occurring on the extremities or trunk of a young adult. Histopathologically, DF is characterized by the presence of different cell types in varying proportions, including fibroblastic cells, histiocytic cells, and even multinucleated giant cells1. In some instances, the tumor may take on a pattern resembling that of dermatofibrosarcoma protuberans (DFSP). Therefore, based on the clinical presentation and routine hematoxylin and eosin-stained sections, the differential diagnosis of DF versus DFSP can be problematic2. A large number of ancillary laboratory techniques have been investigated as potential aids in this differential diagnosis. In the previous and present studies, the combined immunohistochemical results of CD34 and factor XIIIa (FXIIIa) were found to be reliable, but the diagnostic value of this combination is still not considered absolute3,4. There is also considerable controversy regarding the cell of origin of DF. A number of previous studies showed that DF lesions originate from fibroblasts, whereas others pointed to an origin from histiocytes, perivascular cells, or primitive mesenchymal cells5. Recently, it was suggested that dermal dendritic cells play an important role in the histogenesis of DF6. Fibrocytes are a recently identified cell population that represent 0.1%~0.5% of peripheral blood leukocytes. Fibrocyte ZNF35 biology has been implicated in wound healing and in many aberrant fibrosis Erlotinib mesylate diseases states, including hypertrophic scarring and keloids; airway remodeling in asthma; interstitial pulmonary fibroses; systemic fibroses; atherosclerosis; and the stromal response to tumor invasion7. We postulated that fibrocytes might be associated with DF because they are derived from CD14+ Erlotinib mesylate monocyte as dermal dendritic cells8 and histiocytes are. However, there has been no study of the association between fibrocytes and DF to date. The present study attempted to determine the expression of leukocyte-specific protein 1 (LSP1), a fibrocyte marker9, in DF. Additionally, we evaluated the usefulness of LSP1 in the differential diagnosis of DF from DFSP. MATERIALS AND METHODS Tissue specimens Formalin-fixed, paraffin-embedded (FFPE) blocks from 20 cases of DF and 20 cases of DFSP were obtained from biopsy records in two university hospitals in Korea. Cases were selected based on Erlotinib mesylate the original diagnosis, and hematoxylin and eosin-stained sections were reviewed to confirm these findings. Immunohistochemical staining Immunohistochemical staining was performed on FFPE tissue sections from each DF and DFSP case using antibodies against LSP1 and FXIIIa. Additionally, to evaluate the immunophenotypes of the constituent cells in DF, we performed immunohistochemistry with a CD68 antibody. Four-micron-thick sections were obtained from FFPE tissues, transferred onto adhesive slides, and dried at 60 for 25 min. The immunohistochemical procedures were performed using a BOND-MAX automatic immunohistochemical staining instrument (Leica Biosystems, Wetzlar, Germany). In brief, following deparaffinization and rehydration of the tissue sections, antigen retrieval was carried out; endogenous peroxidase Erlotinib mesylate was blocked; and the slides were then incubated for 15 min at room temperature with primary antibodies against LSP1 (mouse monoclonal antibody 16/LSP-1, 1 : 250; BD Transduction Laboratories, San Jose, CA, USA), FXIIIa (mouse monoclonal antibody E980.1, 1 : 100; Novocastra, Newcastle, United Kingdom), and CD68 (mouse monoclonal antibody PG-M1, 1 : 500; DAKO, Glostrup, Denmark). Thereafter, sections were incubated with a polymer detection kit. Diaminobenzidine was used as a chromogen, and the sections were counterstained with hematoxylin. Semiquantification of positive cells was based on the average cell number of 10 high-power fields per section, using a 10 eyepiece and 10 objective lens. Scores were assigned as follows: 0, 5% positive cells; 1+, 6%~33% positive cells; 2+, 34%~66% positive cells; and 3+, 67% positive cells. Statistical analysis was performed using IBM SPSS Statistics 20.0 (IBM Co., Armonk, NY, USA). The chi-squared test was performed to determine a significant difference in the expressions of LSP1 and FXIIIa among the cases of DF and DFSP. A value of em p /em 0.05 was considered statistically significant. RESULTS There were 20 cases of DF, comprising 12 female and 8 male patients, with an average age of 34.3 years (range, 20~79 years). In addition, there were 20 cases.