Acquired reactive perforating collagenosis in association with non-Hodgkin lymphoma: two case reports of a rare association

Acquired reactive perforating collagenosis (ARPC) is the most common form of acquired perforating dermatoses. These are uncommon and underdiagnosed clinical entities characterised by trans epidermal elimination of degenerate collagen, elastin and other connective tissue components. It primarily affects individuals with underlying systemic conditions, most notably diabetes mellitus and chronic kidney disease, particularly those undergoing dialysis. ARPC presents clinically as pruritic, hyperkeratotic papules and nodules, often with central umbilication or crusting, predominantly appearing on the extremities, trunk and areas subject to repetitive trauma or friction, which are believed to trigger or exacerbate the disease. The pathogenesis remains unclear, but trauma, microangiopathy and metabolic disturbances are thought to contribute to its development. Diagnosis is confirmed through histopathology, revealing collagen extrusion through the epidermis. Despite various therapeutic measures, the curative effect is not satisfactory and symptoms can only be improved rather than cured. Here we report a new observation of ARPC occurring in two patients with non-Hodgkin lymphoma.