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LYMPHOMATOID PAPULOSIS (biopsy #1) from a patient who has the findings of PITYRIASIS LICHENOIDES ET VARIOLIFORMIA ACUTA in another biopsy(#2)

Lymphomatoid papulosis (LyP) is characterized by the distinctive combination of:

Clinical features resembling pityriasis lichenoides et varioliformis acuta/chronica.
The pathology of an atypical lymphocytic lesion. The atypia may reside in the resemblance to mycosis fungoides and/or severe cytologic atypia of lymphoctyes. Ki 1+ (CD30) cells are present, but are nonspecific.

Clonal populations of T-cells with rearrangement of T-cell receptor genes (beta and/or gamma) are seen in most cases.

Although LyP is relatively rare in childhood, it can occur in all age groups. Various reports indicate a 10%-20% incidence of the subsequent development of a lymphoma in patients who present with LyP. This incidence appears to be less frequent in the cases that present in childhood, but there have been so few pediatric cases reported with follow up information that one cannot make a blanket statement to this effect. The lymphomas that have developed have included Hodgkin's disease, mycosis fungoides, and other non-Hodgkin's lymphomas.

Opinions regarding the relationship of LyP to pityriasis lichenoides et varioliformis acuta (PLEVA) are varied and contradictory. There is one school of thought that states that LyP is a Ki 1+ lymphoma and that PLEVA is a totally unrelated inflammatory disease. It should be mentioned that clonal populations of T-cells with rearrangement of the gamma T-cell receptor gene have been found in PLEVA¹. Although uncommon, there have been cases of PLEVA associated with the development of lymphoma. Therefore, there is also the opinion that LyP and PLEVA are members of a group of T-cell proliferative disorders that have the potential for the association with lymphoma development. The risk is the least for children with PLEVA and the most for adults with LyP.

The current case is of interest in that one biopsy showed lymphomatoid papulosis with features of PLEVA, and the other showed PLEVA with very few atypical cells that probably would have been overlooked on routine examination.

This 8 year old male developed multiple erythematous papules on the trunk and extremities. Some of these formed a crust. The clinical impression was pityriasis lichenoides et varioliformis acuta. This is a biopsy of one of the crusted lesions.

This biopsy demonstrates one form of cytologic atypia of lymphocytes that, when combined with the clinical presentation, is diagnostic for lymphomatoid papulosis. Extravasated RBC's in the epidermis, necrotic (apoptotic or dyskeratotic) keratinocytes, keratinocyte enlargement, liquefaction (vacuolar) change in the basal layer of the epidermis, and holes in some of the keratinocytes are features of PLEVA.

This scan power view shows a crust over the central part of the lesion, and this corresponds to an area of necrosis of the infundibulum of a hair follicle and adjacent epidermis. The vertical blue area is a hair follicle that is infiltrated by lymphocytes having the features seen in the other photographs.

A medium power view of the epidermis and papillary dermis to the left of the focus of superficial necrosis. Note the keratinocyte enlargement, liquefaction change at the dermoepidermal junction, atypical lymphocytes, necrosis of a few keratinocytes, and extravasation of red blood cells. PMN's are in the upper right side of the picture. There are holes in the cytoplasm of some of the keratinocytes.

A high power view of above. This better illustrates the keratinocyte enlargement, atypical lymphocytes, necrotic (apoptotic) keratinocytes, extravasated RBC's, holes in the keratinocytes, and vacuolar change at the dermoepidermal junction.

A very high power view of some of the lower epidermis and superficial papillary dermis illustrating the morphology of some of the atypical lymphocytes. Such cells were also found adjacent to blood vessels (you can see the distribution in the scanning power view).

Reference:
1: Dereure O, Levi E, Kadin ME. T-Cell clonality in pityriasis lichenoides et varioliformis acuta: a hereroduplex analysis of 20 cases. Arch Dermatol. 2000 Dec;136(12):1483-6.

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	This scan power view shows a crust over the central part of the lesion, and this corresponds to an area of necrosis of the infundibulum of a hair follicle and adjacent epidermis. The vertical blue area is a hair follicle that is infiltrated by lymphocytes having the features seen in the other photographs.
	A medium power view of the epidermis and papillary dermis to the left of the focus of superficial necrosis. Note the keratinocyte enlargement, liquefaction change at the dermoepidermal junction, atypical lymphocytes, necrosis of a few keratinocytes, and extravasation of red blood cells. PMN's are in the upper right side of the picture. There are holes in the cytoplasm of some of the keratinocytes.
	A high power view of above. This better illustrates the keratinocyte enlargement, atypical lymphocytes, necrotic (apoptotic) keratinocytes, extravasated RBC's, holes in the keratinocytes, and vacuolar change at the dermoepidermal junction.
	A very high power view of some of the lower epidermis and superficial papillary dermis illustrating the morphology of some of the atypical lymphocytes. Such cells were also found adjacent to blood vessels (you can see the distribution in the scanning power view).