Hemophagocytic lymphohistiocytosis syndrome secondary to systemic hydroa vacciniforme lymphoproliferative disorder: a case report and literature review

Objective To report a case of hemophagocytic lymphohistiocytosis syndrome (HLH) secondary to systemic hydroa vacciniforme lymphoproliferative disorder (systemic HVLPD) and review relevant literature, in order to improve understanding of the disease. Methods Clinical data of the case, laboratory examination, histopathology, immunohistochemistry, TCR gene rearrangement, and whole exon gene sequencing were collected for analyses. Results A 19 years old man was admitted to the hospital due to generalized papules, blisters, necrotic scabs and fever for 7 months. The clinical manifestations included hydroa vacciniforme-like rashes, lymphadenopathy, splenomegaly, pancytopenia, hypertriglyceridemia, decreased NK cell activity, high levels of sIL-2r, positive for VCA-IgA and EA-IgA, and elevated EBV DNA load. The whole exon sequencing did not show pathogenic gene mutations. Histopathological changes in the skin lesions included liquefaction degeneration of epidermal and follicular basal cells, pigmentary incontinence, lymphocytic infiltrates of the epidermis and follicular epithelium, perivascular and perifollicular infiltrates of lymphocytes and eosinophils in the dermis, extravasation of erythrocytes, as well as focal infiltrates of atypical lymphoid cells around appendages and small blood vessels. Pathologic mitosis was visible. Immunohistochemistry showed CD3 (+), CD5 (+), CD20 (individual+), CD30 (small patch+), CD79a (individual+), CD4 (+), CD7 (+), CD8 (+), TIA-1 (+), CD56 (scattered lymphocyte+), ≈50% of Ki-67(+), and in situ hybridization EBER (+). TCRβ gene monoclonal rearrangements were detected. According to the results of clinical and auxiliary examination, patient was diagnosed with HLH secondary to systemic HVLPD. After 8 months of follow-up, the patient passed away while waiting for transplantation of allogeneic hematopoietic stem cells. Conclusions Systemic HVLPD is rare and requires vigilance for the development of secondary hemophagocytic syndrome. The awareness of hemophagocytic syndrome should be improved to avoid possible misdiagnosis and delayed treatment.