Case Description
The first patient is a 14-year-old female with a clinical history of tumid lupus (biopsy proven at age 2) on immunomodulator treatment, who presented with a 3-year history of progressive cutaneous plaques, subcutaneous nodules, and ulcerations on the left forearm. Serologic studies were negative for auto-antibodies. PET/CT scans demonstrated avidity of skin lesions and two minimally enlarged axillary lymph nodes without additional lesions. The patient had a history of intermittent fevers, occasional malaise and mild cytopenia, which improved without intervention, and elevated CXCL9 on an inflammatory cytokine workup. The biopsy of one plaque showed features of lobular panniculitis, while another biopsy of an ulcerated skin lesion revealed an epidermal ulceration and subcutaneous lobular panniculitic pattern with marked γδ T cell infiltrates rimming the adipose tissue, with a high Ki67 proliferation rate. T-cell gene rearrangements were clonal. NGS studies for both germline and somatic pathogenic mutations were negative. The overall findings favored a SPTCL with increased γδ T-cells (Figure 1). The patient received immunomodulation therapy and with close follow up, disease progression was not observed.
The second patient was diagnosed with stage 1B hypopigmented mycosis fungoides with a γδ T-cell variant at approximately 5 years old. After seven years of follow up, the patient’s skin lesions did not appreciably progress. The third patient is a 6-year-old male who presented with a three-monthly history of extensive hyperpigmented macules on the trunk and extremities and hypopigmented patches on the face. Skin biopsy revealed parakeratosis, psoriasiform epidermal hyperplasia with minimal spongiosis, exuberant lymphocyte exocytosis with epidermotropism, and a perivascular lymphohistiocytic infiltrate in dermis. Immunohistochemical stains revealed an atypical population of CD3+ T-lymphocytes with diminished CD4, CD8, CD5 and CD7 expression within the epidermis. Molecular studies for T-cell gene rearrangements were clonal. A diagnosis of cutaneous T cell lymphoma was suspected. However, additional immunostaining for TCR-delta highlighted that the atypical T-cell population were γδ T cells in nature. The overall findings favored a diagnosis of γδ variant of pityriasis lichenoides (Figure 2). The skin lesions were fully resolved after PLC treatment (azithromycin and triamcinolone ointment).