Pathologic features useful in distinguishing primary cutaneous anaplastic large cell lymphoma (ALCL) and lymphomatoid papulosis (LyP).
| Histology/ Immunophenotype . | LyP . | ALCL . |
|---|---|---|
| Abbreviations: EMA, epithelial membrane antigen; ALK, anaplastic lymphoma kinase | ||
| Modified from Kinney and Kadin, 199942 | ||
| Pattern of infiltration | Wedge-shaped perivascular/ periadnexal | More diffuse |
| Subcutaneous involvement | Absent or minimal | Present |
| Mixed inflammatory cells | Many | Few to many |
| CD30+ cells | Scattered single or small clusters | Large groups or sheets |
| EMA | Present in 10-30% of cases | Present in 10-30% of cases |
| ALK | Usually negative | Usually negative |
| Histology/ Immunophenotype . | LyP . | ALCL . |
|---|---|---|
| Abbreviations: EMA, epithelial membrane antigen; ALK, anaplastic lymphoma kinase | ||
| Modified from Kinney and Kadin, 199942 | ||
| Pattern of infiltration | Wedge-shaped perivascular/ periadnexal | More diffuse |
| Subcutaneous involvement | Absent or minimal | Present |
| Mixed inflammatory cells | Many | Few to many |
| CD30+ cells | Scattered single or small clusters | Large groups or sheets |
| EMA | Present in 10-30% of cases | Present in 10-30% of cases |
| ALK | Usually negative | Usually negative |