AN UNUSUAL CASE OF HEMOPHAGOCYTIC LYMPHOHISTIOCYTOSIS ASSOCIATED WITH M.CHIMAERA OR LARGE CELL NEUROENDOCRINE CARCINOMA

ABSTRACT

CASE 56-year-old Caucasian male presented to the hospital with worsening weakness, exertional dyspnea, dry and nonproductive cough, and a 5-pound weight loss in 2 weeks associated with loss of appetite. He has a significant medical history of mitral valve repair in July 2014, status post bioprosthetic mitral valve replacement in August 2019- culture-negative treated with ceftriaxone, vancomycin, and doxycycline for 6 weeks complicated with CVA, atrial flutter, tobacco abuse, alcohol abuse. His shortness of breath worsened quickly with O2 saturations dropping to 85% and had to be placed on BiPAP followed by high flow nasal cannula/ noninvasive ventilation and became febrile. He was then transferred to ICU for acute hypoxemic respiratory failure. Differentials could be very broad ranging from infections like visceral leishmaniasis, atypical/tuberculous mycobacteria, histoplasmosis, Ehrlichia, Bartonella, Brucella, adeno, disseminated HSV, hematological like Langerhans cell histiocytosis, multicentric Castleman disease. In this patient, differentials included hemophagocytic lymphohistiocytosis, COVID-19. Covid was negative x2. His lab abnormalities as well as diagnostic testing revealed hemophagocytic lymphohistiocytosis. He was empirically started on antibiotics and dexamethasone 20 mg to be continued for 2 weeks then taper if the patient has continued improvement. Dexamethasone was tapered over 8 weeks. On later admissions, Carious test was positive for M. chimaera, and core biopsy of the lung nodule showed large cell neuroendocrine carcinoma. IMPACT/DISCUSSION: Hemophagocytic lymphohistiocytosis (HLH) is a rare but very dangerous condition, characterized by abnormal activation of the immune system, causing hemophagocytosis, inflammation, and potentially widespread organ damage. The primary (genetic) form, caused by mutations affecting lymphocyte cytotoxicity, is most commonly seen in children. Secondary HLH is commonly associated with infections or malignancies. Most current information on diagnosis and treatment is based on pediatric populations. The HLH-2004 diagnostic criteria are the most commonly used diagnostic criteria and were developed for children;but used in adults as commonly as in children, although there is a gap in the knowledge. The HLH-2004 diagnosis criteria state that diagnosis of HLH can be established if either a molecular diagnosis is made consistent with HLH or diagnostic criteria for HLH is fulfilled, which includes meeting 5 of 8 criteria. These are lab and clinical findings including fever, splenomegaly, significant cytopenia, hypertriglyceridemia and/or hypofibrinogenemia, hemophagocytosis in bone marrow/spleen or lymph nodes, low or no NK cell activity, ferritin >500 ug/L or sCD25 >2400 U/mL. CONCLUSION: HLH is a disease that needs to be diagnosed and treated promptly, it is fatal otherwise. Treatment is mostly tailored to the patient's root cause, treat the cause, and symptomatic treatment with dexamethasone and etoposide.