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).