Primary Cutaneous Acral-type CD8-positive T-cell Lymphoproliferations: Widely Divergent Clinical Outcomes Despite Nearly Identical Histomorphology

Abstract Introduction/Objective Non-epidermotropic and acral CD8(+) T-cell proliferations have recently been reclassified as lymphoproliferative disorders (LPDs) due to their indolent course clinical. Here, we describe two cases with similar histomorphology but disparate clinical outcomes, highlighting the diagnostic challenges. Methods/Case Report Case 1: An 89-year-old male developed a 2 cm erythematous papule on the forehead. Biopsy showed a non-epidermotropic pan-dermal lymphocytic infiltrate, a distinct grenz zone, and areas of necrosis. Case 2: A 53-year-old male presented with a rapidly growing, ulcerating 8.9 cm scalp lesion. Biopsy showed a deep dermal lymphoid infiltrate with complete epidermal sparing. In both cases neoplastic cells were positive by immunohistochemistry for CD2, CD3, CD5, CD7 (partial), CD8, granzyme B, TIA-1, and CD68 (perinuclear dot-like pattern). The Ki-67 proliferation index varied modestly between cases (50% in case 1 and 70% in case 2, respectively). Despite treatment, within the span of a few months, case 2 developed adjacent, widely distributed scalp nodules with extensive local tissue destruction. Pathology was consistent with recurrent disease (flow cytometry demonstrating T-cells, co-expressing CD8, CD2, CD3, CD5, CD7 and monotypic TRBC1). Results (if a Case Study enter NA) NA Conclusion CD8+ T-cell lymphoproliferative disorders, specifically primary cutaneous acral CD8+ T-cell lymphoproliferative disorder, is a rare cutaneous T-cell disorder that was re-classified, owing to its indolent clinical course, low risk of systemic dissemination, and favorable prognosis. We report two cases of nearly identical isolated cutaneous lesions that demonstrated a CD8(+)-cytotoxic phenotype with CD68-dot-like positivity. Although all morphologic findings were supportive of the diagnosis, the aggressive clinical progression in case 2 highlights the potential for the disease to defy the classically described indolent behavior. Given that few cases with aggressive clinical courses have been published, we present these cases to underscore their complexity and propose that the classification incorporate clinicopathological correlation to guide management.