S13C9P7Lymphoproliferative


S13C9P7-1: The patterns are psoriasiform and lichenoid. Perhaps, the spaces among the keratinocytes might be characterized as inter-cellular edema (which then might be translated as spongiosis), but the diffuseness of the infiltrates in the epidermis presents a pattern that is best characterized as lichenoid (primary lichenoid type). In turn, the combination of psoriasiform and lichenoid features might then be characterized as a pityriasic quality. The infiltrates in the papillary dermis are loose, but diffuse (band-like); they extend along vessels into the upper portion of the reticular dermis. There are collections of extravasated red blood cells in both the epidermis and the papillary dermis. In evaluating these patterns, pityriasis lichenoides et varioliformis acuta should certainly be mentioned in the differential diagnosis.



S13C9P7-2: The patterns again are pityriasic with a rounded (spongiotic), cell-rich defect as an additional feature. The rounded defect is in continuity with an area in which the spaces among keratinocytes are widened (edematous pattern). On the basis of the cell-rich character of the epidermal infiltrate beneath the rounded defect, some observers, when employing “pattern analysis” at low magnification, might simply assign the lesion to the category of “cutaneous T-cell lymphoma” (CTCL). The richness of cells in the underlying basal unit of the epidermis does not exclude a pityriasic reaction, as opposed to cutaneous T cell lymphoma. Additional clues are required; for this example, pattern analysis at low magnification would be insufficient (as it often is).

S13C9P7-3: At higher magnification, the lymphoid cells in the epidermal infitrates are atypical. The nuclei of many of the lymphoid cells are enlarged and irregular in outline. Chromatin patterns are open and nuclear membranes are “heavy” (broad and dense). Even with this degree of atypia, it would be difficult to exclude a variant of pityriasis lichenoides. Clinical features would be an aid in the interpretation.

S13C9P7-4: Large atypical lymphoid cells are sprinkled among smaller lymphoid cells in the dermal infiltrates. Some of the large cells are interstitial in distribution. The cytological features and the distribution of the cells in the dermal infiltrates can be combined to form a parcel, the components of which would be in keeping with the changes often seen in lesions of lymphomatoid papulosis. Although many observers now claim that lymphomatoid papulosis is separate, and distinct, from pityriasis lichenoides, for this example, the distinctions are somewhat difficult to define.

S13C9P7-5: In this field in the dermis, the infiltrates are pleomorphic; there are scattered large, atypical cells (red arrow). Many of the small lymphoid cells are also atypical; they show variations in nuclear size and outline. The green arrow points to a mitotic figure (pityriasic lymphoproliferative disorder). There are extravasated red blood cells (pityriasic quality).

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