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Correspondence to Dr Danielle R Rinck; [email protected]
Introduction
Primary cutaneous peripheral T-cell lymphoma, not otherwise specified (pcPTCL-NOS) is a group of T-cell lymphomas that does not fit the criteria of other primary cutaneous T-cell lymphomas (PCTCLs) defined by the WHO. The immunophenotype of the neoplastic T-cells can vary, with some cases showing aberrant expression of CD20. The diagnosis is exceedingly rare, and the prognosis is poor.1
Case report
An elderly female patient with a complex medical history, including peripheral artery disease and chronic wounds secondary to venous stasis, presented with worsening right lower extremity wounds despite outpatient antibiotic treatment (figure 1). She developed hypotension, hypoxia and leukocytosis concerning for sepsis and was admitted for intravenous antibiotic therapy. She was noted to have a generalized rash during her admission consisting of fixed, discrete pink plaques on her trunk and extremities. A skin biopsy was recommended; however, the patient was discharged with a plan for close outpatient follow-up. Unfortunately, she missed her outpatient visit and then presented a month later with acute kidney injury, worsening rash and multipressor shock requiring intubation and sedation. Her rash had coalesced and focally ulcerated; she had also developed discrete tumours (figure 2). Punch biopsies were obtained for more definitive evaluation.
Histopathology revealed a superficial to deep dermal sheet-like infiltrate composed of medium to large abnormal lymphoid cells with irregular nuclear contours. The neoplastic cells extended to the subcutis (figure 3). By immunohistochemistry, the neoplastic cells were positive for CD3, CD5 and CD43 and showed aberrant CD20 expression. They stained dim/subset variable for CD25 and PD-1, subset dim granular for perforin and scattered (rare positive cells) positive for BCL6 (5%). The neoplastic cells stained negative for CD2, CD4, CD7, CD8, CD10, CD19, CD21, CD23, CD30, CD56, CD79a, PAX-5, TCR-delta, TIA-1 and granzyme B. Ki-67 proliferation index was high (approximately 90%) (figure 4). In situ hybridization for Epstein-Barr virus encoded RNA was negative. The immunohistochemical positivity for both CD3 and CD20 was unexpected and raised the differential of both a T-cell and a B-cell neoplasm. T-cell receptor (TCR) gamma gene rearrangement was positive...