LyP Three histologic types of LyP have been described: types A, B and C. D ?

LyP type A A wedge-shaped Extensive inflammatory infiltrate composed of small lymphocytes, neutrophils and/or eosinophils Initially non-epidermotropic infiltrate Scattered or small clusters of large atypical, sometimes multinucleated or Reed–Sternberg-like, CD30+ T cells

LyP type A The large atypical cells seen in C-ALCL, are relatively few in early lesions and more numerous in fully developed lesions, but may be completely absent in resolving lesions. The presence of scattered neutrophils within a moderately acanthotic and parakeratotic, but otherwise unaffected, epidermis is a characteristic finding.

LyP type B Uncommon (<10%) Characterized by superficial perivascular to band-like lymphocytic infiltrates Perivascular infiltrates can also be found in the deeper dermis. The infiltrates are composed predominantly of small to medium-sized atypical cells with cerebriform nuclei and the phenotype of CD3+, CD4+, but CD30−, T cells, similar to those observed in MF

LyP type C Monotonous population or large clusters of large CD30+ T cells Relatively few admixed inflammatory cells, a histologic appearance typically found in C-ALCL

LyP type D Marked epidermotropism is seen histologically indistinguishable from primary cutaneous aggressive epidermotropic CD8+ cytotoxic T cell lymphoma

A,C have large atypical blasts (mono- or bi-nucleated ) resembling reed sternberg cells of hodgkin lymphoma which express CD 30 antigen In type A impedded in dense inflammatory infiltrate but in type C form sheets resembling ALCL Type C, small to medium CD30 –ve T cells with epidermotropism which resemble MF Clinical picture can differrntiate LyP from ALCL

Aim From a practical point of view, histologic subtyping is not necessary, since the three histologic subtypes do not differ clinically Classification helps to understand the relationship between LyP and other types of CTCL and to the definition of the spectrum of primary cutaneous CD30+ lymphoproliferations.

Risk Associated lymphomas, either before, after, or concurrently with the development of LyP, were observed in 23 of 118 (19%) patients The calculated risk for systemic lymphoma within the first 10 or 15 years after diagnosis was 4% and 12%, respectively, in contrast with the 80% at 15 years in a study of Cabanillas et al