Primary Cutaneous CD4-Positive Small/Medium Pleomorphic Lymphoproliferative Disorder in skin
Lessons From the Friday Unknowns
The patient is a healthy 6 year old boy who developed a persistent red papule on his left cheek 5 months ago.
Histologic sections show a dense, dermal lymphocytic infiltrate involves full-thickness of dermis, with focal extension into superficial subcutaneous tissue and with a narrow zone of relatively uninvolved superficial dermis (Grenz zone) present above the infiltrate and beneath the overlying epiderrmis.
The atypical lymphocytic infiltrate comprises pleomorphic lymphocytes of small, intermediate and large size, with relative predominance of pleomorphic, small and intermediate lymphocytes. Approximately 15% of pleomorphic lymphocytes are of large size.
Immunohistologic staining shows positive immunoperoxidase staining of the amorphic lymphoid cells for CD4 and CD3, with non-immunoreactivity of these cells for CD8. Moderate number of small morphologically normal lymphocytes shows positive immunostaining for CD8. A moderately large number of lymphocytes within the infiltrate are B cells immunoreactive for CD20. Immunohistologic staining for CD30 and ALK protein is negative.
Molecular genetic (PCR) testing and paraffin tissue from the block gave a positive result for clonal T-cell receptor beta gene rearrangement as well as a positive result for clonal T-cell receptor gamma gene rearrangement.
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Link to digital slides: bit.ly/3NbSQ8r | Case 1