Fanconi anemia in 55‐year‐old identical twins first presenting as fatal post‐chemotherapy pancytopenia
Authors: Hannah Stevens, Chong Chyn Chua, Mathew Wallis, Simon Hew, Andrew Grigg
Journal: American Journal of Hematology (2016)

A 55-year-old male presented with a two-day history of fevers and rigors. He reported mild nausea but otherwise no focal infective symptoms. Ten days previously he had received transarterial chemoembolization (TACE) for hepatocellular carcinoma. The chemotherapy consisted of mitomycin C 10 mg, cisplatin 50 mg, doxorubicin 50 mg, and lipiodol 10 mg. The patient had clinical features of sepsis without localizing signs and was urgently commenced on empirical broad-spectrum intravenous antibiotics with piperacillin-tazobactam. The diagnosis of hepatocellular carcinoma (HCC) was made 6 months earlier on a background of biopsy-proven nonalcoholic noninfective steatohepatitis without cirrhosis. Other past medical history included an asymptomatic horseshoe kidney noted since childhood and diet-controlled diabetes mellitus. The patient was of Italian descent, born to parents who were non-consanguineous and had a monozygotic twin brother. The temporal association with chemoembolization raised a high suspicion of a TACE related complication. TACE is one of the major treatment modalities for patients with unresectable but localized HCC with preserved liver function. It involves targeted delivery of chemotherapy into a branch of the hepatic artery supplying the tumor, followed by embolization of the artery to ensure intratumoral drug retention and minimal systemic adverse effects. Favorable tumor responses range from 35 to 60% 1. Complications of TACE can be divided into vascular and nonvascular events 2. Vascular complications include puncture site issues, hepatic artery damage (arterial perforation or ulceration) and inadvertent systemic embolization. Nonvascular complications include postembolization syndrome (fevers, nausea, right upper quadrant pain, transient elevation of liver transaminases) which may occur in up to 90% of patients, both localized and systemic infections, hepatic decompensation, and pulmonary embolization through arteriovenous or portovenous shunting resulting in pneumonitis 2. The main differential diagnoses for this patient were sepsis either from a primary hepatic or alternate source, or post-embolization syndrome, although typically this syndrome occurs much earlier postprocedure. Investigations including full blood examination (FBE), biochemistry, liver enzymes, blood cultures, and imaging of the abdomen would be of utmost importance. Pre and post TACE blood investigation results are summarized in Table 1. FBE examination revealed profound pancytopenia, on a background of a mild pre-existing pancytopenia. The blood film did not demonstrate dysplastic features, circulating blasts, fragments, spherocytes, or platelet clumping. Computed tomography with contrast angiogram of the abdomen only revealed changes consistent with recent chemoembolization; there was no portal hypertension or splenomegaly. Cytopenias following TACE are uncommon with occurrence in less than 3% 3, but severe pancytopenia has not been described previously. Hypothetically this may occur as a result of substantial systemic absorption of the chemotherapeutic agents and their subsequent myelosuppressive effects or modest systemic exposure in patients with pre-existing marrow pathology. Systemic absorption can theoretically occur if a nontarget artery is selected for delivery of chemotherapy, an arterial shunt is present or embolization of the target artery is unsuccessful. Primary and secondary causes of severe pancytopenia need to be excluded in this patient, most commonly drug-induced or immune-related aplastic anemia or, less likely given the time course, marrow infiltration due to malignancy. In the absence of diagnostic features on the peripheral blood smear a bone marrow biopsy was warranted. The marrow biopsy day 24 post TACE demonstrated marked hypocellularity. There was no evidence of dysplasia, nor a clonal population on flow cytometry and conventional cytogenetics did not reveal any abnormality. On review, mild pancytopenia was first noted during a preoperative work-up for a hip arthroplasty 5 years prior to the current presentation. At the time, investigations including viral hepatitis serology, anti-nuclear antibody, and paroxysmal nocturnal hemoglobinuria screen were negative. Vitamin B12 and folate levels were normal. No culprit medications were identified. A marrow biopsy demonstrated a hypoplastic marrow (20% cellularity), with no evidence of dysplasia or megaloblastosis and conventional cytogenetic analysis was normal. A single dose of granulocyte colony-stimulating factor (G-CSF) 300 μg was administered with appropriate transient increase in neutrophil count from 0.9 × 109/L to 6.9 × 109/L. The pancytopenia remained stable over the following 5 years and did not require any further G-CSF or blood product support. The history of long-standing pancytopenia added a further dimension to the clinical case and raised suspicion for an underlying bone marrow disorder such as hypoplastic myelodysplastic syndrome or aplastic anemia; despite the patient's age, an inherited cause of bone marrow failure was considered. Fevers persisted over the following weeks despite empirical antibiotic therapy with intravenous piperacillin-tazobactam, vancomycin, and gentamicin. Subsequent blood cultures flagged positive for Candida dubliniensis and Candida albicans, which were treated with antifungal agents including anidulafungin and voriconazole. Profound pancytopenia continued despite G-CSF, blood product support and commencement of donor granulocyte infusions. Progressive worsening of the patient's clinical status prompted consideration of a syngeneic peripheral blood stem cell transplantation from the twin brother, confirmed by urgent human leukocyte antigen typing to be identical. Peripheral blood stem cell mobilization from the brother using a combination of G-CSF and plerixafor was unsuccessful with a peak peripheral blood CD34+ count of 2 × 106/L, which is well below the threshold required for an adequate collection. The brother was noted to also have leukopenia and macrocytosis. Further clinical evaluation of both the patient and his brother revealed striking and abnormal physical features, including hypoplastic thenar eminences, short thumbs, short stature, microcephaly, undescended testes requiring orchidopexy, and horseshoe kidneys. (Fig. 1) Both had a history of hip osteoarthritis; in addition, the patient had a history of type 2 diabetes mellitus and the brother a history of infertility. A and B. The hands of the patient and his identical twin brother showing bilateral hypoplastic thenar eminences and short thumbs. [Color figure can be viewed at wileyonlinelibrary.com.] Congruent physical anomalies in combination with bone marrow failure in both the patient and his identical twin strongly suggested the possibility of an inherited bone marrow failure syndrome, despite the brothers being significantly older than the expected age for these syndromes to present. Possible syndromes include Shwachman-Diamond syndrome (SDS), dyskeratosis congenita (DC), Rothmund Thompson syndrome (RTS) and Fanconi anemia (FA). SDS appeared unlikely as the usual presentation involves exocrine pancreatic insufficiency and skeletal abnormalities, which were not evident in this case, although up to 50% of patients with genetically confirmed SDS may not have the classic manifestations 4. DC is characterized by the classic triad of dysplastic nails, lacy reticular pigmentation of the upper chest/neck, and oral leukoplakia 5. The most characteristic feature in RTS is a facial rash (poikiloderma) but patients may also present with short stature, sparse hair, juvenile cataracts, skeletal abnormalities, and radial ray abnormalities 6. The condition that was most keeping with the phenotype with this case was FA, the most common characteristics of which include skeletal abnormalities, abnormal skin pigmentation, short stature, microcephaly, microphthalmia, and renal abnormalities 7, 8. The screening test for FA, chromosomal fragility testing was undertaken and if positive, confirmatory genetic testing for FA was intended. Despite prolonged broad-spectrum antibiotic support, the patient died of overwhelming sepsis day 32 post TACE. Chromosome fragility testing on the surviving twin brother was positive. Subsequent testing with chromosomal microarray documented three long contiguous stretches of homozygosity, representing 1% of the genome. A search within these regions highlighted RAD51C and BRIP1 as possible candidate genes. Whole exome sequencing with bioinformatically targeted analysis of the FA genes revealed homozygosity for a BRIP1 (FANCJ) missense mutation (p.R251C), confirming the diagnosis of FA. A marrow biopsy of the twin brother demonstrated mild hypocellularity (20%) with reduced trilineage hematopoiesis and mild erythroid dysplasia (<10%). Subsequently the brother and his family were counseled of the need for ongoing surveillance for complications of FA. Through cancer screening, the brother was diagnosed with localized prostate cancer and underwent an uncomplicated total radical prostatectomy with extended lymph node dissection. He did not require any chemoradiotherapy and at the time of this report, he remains well. Guidelines recommend conducting chromosome fragility studies or molecular genetic studies in all full siblings of an affected individual with FA; in this case there were no other siblings 9. The children of the twins were all obligate carriers for a heterozygous missense BRIP1 mutation. Their risk of being affected by FA was unlikely and dependent on their mother's carrier status. FA is a rare recessive condition characterized by a combination of chromosome instability, congenital physical abnormalities, bone marrow failure and a markedly increased propensity for both hematological, and solid organ malignancies 9. FA has a reported incidence of 1 in 160,000–360,000 with an estimated carrier frequency of 1 in 300, and is the most common inherited bone marrow failure syndrome 10. FA is a genetically heterogeneous disorder caused by mutations in at least 16 genes involved in the FA pathway which is responsible for DNA repair, with an X-linked form seen in approximately 2% of cases 11. The most common mutation is the FANCA gene (16q24.3), accounting for up to 70% of FA patients. Chromosomal fragility testing of blood lymphocytes is the accepted screening test 12. Increased breakage and radial forms can distinguish FA from other chromosome breakage syndromes. Skin fibroblasts can also be obtained for culture if the studies on blood lymphocytes are inconclusive and the clinical suspicion remains high. Massively parallel sequencing technologies are now routinely employed to improve the likelihood of arriving at a confirmatory molecular diagnosis in patients thought to have FA. The diagnosis of FA is almost always made in childhood with a median age of 7 years at diagnosis 8. However, the prevalence of FA in the adult population is largely unknown, as adult presentations have only been described in case series and reports. The oldest reported age at diagnosis in the literature is a 56-year-old female who had typical physical features of FA without evidence of malignancy or hematological involvement 13. Pinto et al. performed FA testing on 87 consecutive patients who were referred with bone marrow failure in a single center without typical physical features of FA and confirmed the diagnosis of FA in four adult cases, with age ranging from 26 to 51 years 14. All these patients had only one to two minor physical abnormalities ranging from minor skin changes to short stature 14. Although the classical manifestations of FA have been well described, the diagnosis of FA can be difficult to make due to significant variability in clinical presentation. More common anomalies include short stature, abnormal skin pigmentation such as café au lait spots, microcephaly, malformation of the thumbs and/or radii, genitourinary malformation, microphthalmia, or features of VACTERL 8. The International Fanconi Anemia Registry in 1997 reported approximately one third of patients enrolled lacked any major congenital malformations, although all had evidence of minor malformation when examined by the investigators 15. These observations raise the question as to whether FA is underdiagnosed in the adult population with very subtle physical changes and less severe hematological manifestations. Clinical indicators for FA screening have been developed and certain combinations of features are thought to provide a stronger indication for genetic testing, although these have not been well validated 9. Ultimately, a high degree of clinical suspicion is required to make the diagnosis. In the patient discussed in this report, the diagnosis of FA was only recognized in late adulthood in the context of lethal pancytopenia from localized targeted chemotherapy. The mild stable pancytopenia had resulted in the delayed recognition of diagnosis until the fatal event, although in retrospect the physical features consistent with FA were present. The unusually advanced age at diagnosis in this patient could be explained by the specific genotype. The p.R251C BRIP1 missense mutation is located in the functionally important and highly conserved helicase domain. It has been reported in another patient with FA who was compound heterozygote for a second BRIP1 variant (p.H396D), although the clinical details and age at diagnosis were not reported 16. Most reported patients with FA due to BRIP1 alteration have truncating mutations rather than missense mutations, and were diagnosed in childhood 17, 18. It is possible that the p.R251C mutation in our case is a hypomorphic FA mutation that encodes a protein with residual function leading to a less severe phenotype, but this has not been confirmed with further studies. To our knowledge, this is the first case to report fatality from pancytopenia secondary to targeted localized chemotherapy delivery method with theoretically minimal systemic exposure. A similar case of late diagnosis of FA in a 33-year-old female was previously reported after fatal pancytopenic sepsis following systemic chemoradiotherapy in combination with an investigational tyrosine kinase inhibitor for T2N2b head and neck squamous cell carcinoma 19. The inherent chromosomal instability in FA patients renders them exquisitely sensitive to DNA toxic agents such as chemoradiotherapy 20. As the heightened risk of malignancy in FA greatly increases the chance of exposure to such agents it is important to make the correct diagnosis beforehand. Peripheral blood stem cell mobilization was unsuccessful in the twin brother with very mild pancytopenia, consistent with compromised stem cell reserve. Peripheral blood stem cell mobilization has been evaluated in eight pediatric patients with FA prior to the development of pancytopenia 21. Two patients were unable to proceed to collection due to insufficient peripheral blood CD34+ count 21. The remaining six patients required extended mobilization with G-CSF and an average of four apheresis sessions to achieve the target CD34+ yield 21. The median overall survival in patients with FA is estimated to be 30 years of age with mortality most often due to complications of severe bone marrow failure10. Butturini et al looked at 388 patients with FA and found that the risk of developing hematopoietic abnormalities or MDS/AML by 40 years of age was 98 and 52%, respectively 22. With increasing age, the risk of solid organ malignancies increases, the most common of these being squamous cell carcinomas of the esophagus, oropharynx, and vulva 7. Carriers of FA are asymptomatic, although some harbor an increased risk of malignancy due to particular genotypes, most notably BRCA2 (FANCD1) mutation and truncating mutations in BRIP1 23. Achieving a molecular diagnosis can benefit the patient and their family through targeted disease surveillance, early diagnosis in at-risk relatives, identification of a couple's recurrence risk and affording them reproductive options, and identifying potential bone marrow donors. Genetic counseling should be arranged for any patient thought to have FA and for their close family when the diagnosis is confirmed. This case highlights the importance of performing a careful assessment of adult patients with evidence of bone marrow failure for physical anomalies suggestive of an underlying inherited syndrome. The diagnosis of FA is crucial in these patients to avoid or minimize potential fatal complications from exquisite sensitivity to chemoradiotherapy agents, particularly in the context of an increased risk of malignancy.