The patient was a 23-year-old male of Turkish/Kurdish descent of consanguineous parents (second-cousins) who had 4 healthy siblings and one sister with a rare lung disease not immediately associated with the patient's condition. His parents had lost a child at a few months of age with no certain diagnosis.
The patient had skin lesions from 2 years of age, affecting his face and extremities and to a lesser degree his truncus. The lesions appeared as purple plaques of the skin with variable thickness evolving into deep atrophic scars over time. There had been numerous biopsies over the years showing an uncharacteristic massive lymphoid infiltration dominated by CD8+ lymphocytes and histiocytes and with some granulomas (Figure 1). In lack of a more precise histopathological diagnosis and considering the clinical presentation, a diagnosis of sarcoidosis was given. Despite aggressive immunosuppressive therapy including corticosteroids, methotrexate, azathioprine, and anti-TNF agents, the lesions gradually evolved although in a slow and undulating manner. In a reevaluation of the skin biopsies, the pathologists found a diffuse lymphohistiocytic infiltrate dominated by CD8+ T-cells with several different monoclonalities as well as epithelioid cell granulomas. They concluded with a T-cell dominated lymphoproliferative state associated with a form of primary immunodeficiency, for example, a RAG-mutation. Meanwhile the patient underwent carmustine therapy on the suspicion of mycosis fungoides without any apparent clinical effect. One year before presentation at Oslo University Hospital, the patient was found to have a diffuse large cell B-cell lymphoma (non-GC-B type, EBV+) in a tumor of the neck and at the same time another different B-cell lymphoma (unclassifiable, with features intermediate between diffuse large-B cell lymphoma (DLBCL) and classical Hodgkin lymphoma) preauricularly (Figure 2). PET-CT showed a possible lymphoma in the right lung, and as such he was staged as IVA, aaIPI 1. He underwent chemotherapy (R-CHOEP 14x 6 + 2R) and radiation therapy against residual disease and went in complete remission with a negative PET-CT. His skin lesions, however, got worse throughout the chemotherapy and radiation therapy and continued to evolve with infiltration into the masseter muscle in the face and a similar histopathological picture was found in lesions diffusely infiltrating the liver and possibly spleen. The patient had no history of recurrent infections, autoimmunity, or other manifestations of a primary immunodeficiency beside his skin lesions and lymphoma.
At presentation at Oslo University Hospital, he was immunologically characterized by a slight hypogammaglobulinemia (IgG 6,1 g/L) and absence of B-cells in peripheral blood considered to be secondary to rituximab treatment (Table 1). However, low numbers but not absence of B-cells in previous bone marrow biopsies had been noted. He did not receive any immunoglobulin therapy. He was slightly lymphopenic (0,8 x 109/L) and had low levels of CD4+ cells (177 x 106/L) with an inversed CD4/CD8 ratio of 0,63. There was an absence of naive CD4+ T-cells and recent thymic emigrants. His CD8+ cell pool was expanded but had a normal phenotype. He had normal levels of double-negative T-cells and gamma-delta T-cells. Overall the T-cells seemed to be strongly activated with half being HLA-DR+. We have no data on proliferative response to mitogens or specific antigens.
There was a strong clinical suspicion of an underlying immunodeficiency but DNA-sequencing covering exons and introns to the RAG1/RAG2 gene did not reveal any mutations. Samples were taken for whole-exome sequencing, but while waiting for the results, the patient had a DLCBL-like relapse in the gastroventricular mucosa engaging pancreas and spleen with infiltration of irregularly shaped histiocytic cells and T-cells monoclonal for the TCR-gamma chain. Dose-reduced chemotherapy was initiated (isophosphamide, methotrexate, and etoposide), but after 3 days of therapy, a near catastrophic gastrointestinal bleeding occurred from the tumor. He went through extensive surgery and we received report of a homozygous missense mutation in exon 8 of the Artemis-coding gene DCLRE1C (NM_001033855.2: c.632G>T, p.G211V), while he was still in the intensive care unit. Sanger sequencing confirmed homozygosity in patient DNA and heterozygosity in his father and one of his siblings, while his mother was not tested. Fibroblastic culture furthermore revealed radiosensitivity consistent with an Artemis defect. The genetic variant has previously been reported as disease-causing in a patient from a patient cohort with radiosensitive SCID and Omenn syndrome. It has not been observed in databases for normal variation (ExAC and gnomAD).
The affected amino acid is located in the beta-CASP domain of DCLRE1C. Predicted secondary structure suggests that the amino acid is located in a six-amino-acid-sized stretch between a helix and a strand. The amino acid is highly conserved both between species and in members of the beta-CASP domain.
The patient was again evaluated by PET-CT and considered in complete remission after surgery and referred for HSCT. He had no severe comorbidity, and the now increasingly aggressive nature of his immunodeficiency made the case for HSCT well founded. None of his siblings were HLA identical and no matched unrelated donor could be identified. For practical reasons, availability as well as identical ABO type, we decided to choose his haploidentical father as the preferred haploidentical stem cell donor. The parents' heterozygosity for the Artemis mutation was considered irrelevant due to the recessive nature of the trait and their apparently normal immune function. Artemis mutated immunodeficiencies in general are likely to tolerate myeloablative conditioning, which gives the best long-term immune reconstitution with thymopoiesis and B-cell function. The options of (A) conditioning with alemtuzumab, treosulfan, fludarabine, and thiotepa using a TCR-alpha and -beta depleted graft versus (B) using a T-cell replete marrow graft after cyclophosphamide 14, 5 mg/kg days -6 and -5, flu 30 mg/m2 days -6 to -2 (5 days), and 200 cGy TBI day -1 with the addition of busulfan 3.2 mg/kg/day, days -4 and -3 to achieve myeloablation as conditioning and posttransplant cyclophosphamide 50 mg/kg days +3 and +4 and tacrolimus and mycophenolate mofetil as graft-versus-host-disease (GVHD) prophylaxis were discussed. We chose the latter option for our patient, and he received BMSC, only 1,7 x 108 NC/Kg, and stable engraftment was achieved at day +18. Donor chimerism was >99% at day 100. The posttransplant course was uncomplicated except for two episodes of CMV reactivation that was preemptively treated.
On Day 150, however, the patient was referred to hospital with fever and lung symptoms with CT scans demonstrating extensive lung infiltrates. Bronchoscopy with bronchoalveolar lavage was performed showing a positive PCR reaction for Pneumocystis jirovecii, and while the immunofluorescence test was negative, a Pneumocystis jirovecii pneumonia (PCP) was highly suspected. PCP prophylaxis with trimethoprim-sulfamethoxazole had been prescribed but the patient had for unknown reasons only taken this on and off. Further tests showed a positive Herpes simplex virus PCR reaction in plasma, and Staphylococcus aureus and Candida albicans were found in blood cultures. The patient was extensively treated with antibiotics including high-dose trimethoprim-sulfamethoxazole as well as corticosteroids and acyclovir. Sadly, however, he did not respond to this treatment and died on day 167. Autopsy was unfortunately not done.