C3d immunohistochemistry is a valuable tool in the diagnosis of BP and PG of the skin with a sensitivity of at least 97%. Mixed forms of linear IgA dermatosis, and BP, DHD and linear IgA dermatosis can only be identified by DIF. A positive result may prompt serologic confirmation of BP without further need for DIF.

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Cutaneous [gamma]/[delta]+ T-cell lymphoma (CGD-TCL) is a rare but aggressive lymphoma associated with a poor prognosis in most patients. The clinicopathological spectrum is variable including predominantly epidermotropic infiltrates manifesting with patches and plaques or tumors with dermal and/or subcutaneous infiltrates. The diagnosis of CGD-TCL requires the demonstration of a [gamma]/[delta]+ phenotype by immunohistochemistry. We report 2 patients with epidermotropic cutaneous T-cell lymphomas displaying a [gamma]/[delta]+ phenotype, but exhibiting an indolent course. In one patient, the clinical presentation was similar to mycosis fungoides in patch and plaque stage, but recurrent blister formation within the lesions was observed accompanied by fever and arthralgias, whereas the second patient presented with 2 localized erosive plaques on the left temple and dense epidermotropic and dermal diffuse and folliculotropic infiltrates of atypical small-to-medium-sized lymphocytes. exhibiting an indolent course. In one patient, the clinical presentation was similar to mycosis fungoides in patch and plaque stage, but recurrent blister formation within the lesions was observed accompanied by fever and arthralgias, whereas the second patient presented with 2 localized erosive plaques on the left temple and dense epidermotropic and dermal diffuse and folliculotropic infiltrates of atypical small-tomedium-sized lymphocytes. These cases corroborate the view that expression of a g/d+ phenotype in cutaneous T-cell lymphomas per se does not portend a worse prognosis and that CGD-TCL may represent a clinically and prognostically heterogeneous group.