Hemophagocytic lymphohistiocytosis: a rare association with pulmonary cryptococcosis

Abstract

Hemophagocytic lymphohistiocytosis (HLH) is an inflammatory syndrome characterised by unregulated macrophage and T-lymphocyte activation, resulting in cytokine overproduction and subsequent histiocytic phagocytosis. Here we report a case of pulmonary cryptococcosis, in a 59-year-old diabetic patient, with no other risk factors whose clinical course was complicated by secondary hemophagocytosis. Even after addressing the primary underlying illness (pulmonary cryptococcosis), his clinical condition continued to worsen. After excluding the other causes of HLH and possible reasons of his clinical worsening, glucocorticoids were added following which the patient experienced a remarkable improvement in his clinical and laboratory parameters. To our knowledge, this is the first case report of HLH being caused by pulmonary cryptococcosis and only second case report of cryptococcosis being complicated with HLH (previous report being associated with meningoencephalitic cryptococcosis).

Background

Hemophagocytic lymphohistiocytosis (HLH) is a disorder characterised by fever, cytopenias, lymphadenopathy, organomegaly, hepatitis and hyperferritinemia due to dysregulated immune system. Acquired/secondary HLH is most commonly triggered by infections and haematological malignancies, viral infections being the underlying cause in up to one-third of cases. Fungal infections are less frequent triggers of HLH, with Histoplasma, Leishmania, Plasmodium and Toxoplasma being the most frequently reported.^1–3 The association of cryptococcal infection with HLH is not well known. Here, we report an adult diabetic male patient of pulmonary cryptococcosis who eventually developed secondary HLH and required glucocorticoids for the treatment of HLH.

Case presentation

A 59-year-old man presented with complaints of fever, dry cough and dyspnoea of 2 months duration. His fever was of low grade with characteristic evening rise of temperature. His cough was associated with two episodes of streaky haemoptysis. Breathlessness was of insidious onset, gradually progressive and was graded 1 on the modified Medical Research Council scale. These symptoms were associated with anorexia and loss of weight (7 kg). He was a known diabetic for past 1 year, on oral hypoglycaemic agents with no history suggestive of end organ damage. He was current smoker with smoking index of 200. He was initially treated by medical practitioner with empirical antitubercular therapy for 1 month, but not had any clinical response.

On examination, the pulse rate was 100 beats/min, respiratory rate 16 breaths per minute, blood pressure 160/90 mm Hg and temperature 37.2°C. Pulse oximetric saturation was 96% while breathing room air. Systemic examination of the respiratory system and other systems was unremarkable.

Complete blood counts, liver function tests and renal function tests were normal at time of presentation. His glycated haemoglobin (HbA1C) was 8.8%, with no proteinuria and no changes of diabetic retinopathy on fundus examination. His chest radiograph showed heterogeneous right perihilar opacity. Contrast-enhanced CT thorax revealed well-defined mass lesion in superior segment of right lower lobe abutting the costal pleura, encasing the right main bronchus and right pulmonary artery with no evidence of pleural effusion or mediastinal lymphadenopathy. High-resolution CT (HRCT) of lung fields showed patchy areas of consolidation and ground glass opacities in bilateral lung (figure 1). He was evaluated initially with the possibility of bronchogenic carcinoma. He underwent flexible optic bronchoscopy which showed extrinsic compression of right lower lobe apical segment bronchus, and endobronchial ultrasound-guided transbronchial needle aspiration was done from the mass lesion. Aspirate was negative for tuberculosis workup (acid-fast bacilli stain and GeneXpert MTB/RIF) and cytological examination showed the presence of giant cells with ill-defined epithelioid granuloma along with the presence of encapsulated fungal elements consistent with cryptococci (figure 2). His CT head was normal and cerebrospinal fluid examination was not done as he did not give consent for the same. HIV ELISA was negative. A final diagnosis of pulmonary cryptococcosis was made and he was started on liposomal amphotericin B 3 mg/kg per day.

Figure 1.

High-resolution contrast-enhanced CT of thorax showing mass-like consolidation at right hilum encasing the right main bronchus and right pulmonary artery (left). Lung window showing patchy areas of consolidation in right middle lobe, right lower lobe and superior lingular segment (right).

Figure 2.

Endobronchial ultrasound-guided transbronchial needle aspiration cytology smears from mass show. (A) Cluster of histiocytes with spherical yeast form of cryptococcus predominantly present intracellularly with reactive lymphoid cells in background (May-Grünwald Giemsa Stain, 200×). (B) Ill-formed granuloma with many variable-sized, rounded yeast cells surrounded by halos with well-appreciated refractile capsule (H&E, 400×). (C) PAS stain-positive cryptococcus yeast cell with blue-coloured capsule and with narrow-based budding (arrow, Alcian Blue-PAS stain, 400×). (D) Cell block section shows many histiocytes and lymphocytes with cryptococcus yeast cells (H&E, 200×).

Treatment

The patient had persistent fever with increased spikes (maximum documented 39°C) and cough after 10 days of therapy and was re-evaluated in view of non-improvement. His repeat chest X-ray showed persistent right perihilar opacity. He underwent repeat bronchoscopy and bronchoalveolar lavage (BAL) was obtained. BAL fluid grew Cryptococcus neoformans var grubii sensitive to amphotericin, fluconazole, itraconazole and posaconazole. His haemogram showed new onset bi-cytopenias (haemoglobin 88 g/L; absolute neutrophil count 980/µL; platelet 156 x10⁹/L) along with raised liver enzymes (alanine transaminase 159 U/L (four times upper limit of normal); aspartate transaminase 84 U/L (two times upper limit of normal); bilirubin 0.33 mg/dL; alkaline phosphatase 307 U/L). His ferritin level was 3099 ng/mL and serum triglyceride was normal. His blood and urine cultures were sterile; procalcitonin level was 0.075 ng/mL. His ultrasound abdomen was unremarkable except for an enlarged spleen of 13.1 cm in length. Bone marrow examination revealed normocellular marrow with increased histiocytes showing hemophagocytosis (ingested granulocytes, erythroblasts, erythrocytes and cell debris). No infectious organisms were seen (figure 3). Other more common causes of hemophagocytosis like Epstein-Barr virus (EBV), cytomegalovirus (CMV), autoimmune diseases and malignancy (IgM CMV, IgM EBV, antinuclear antibody by ELISA-negative) were excluded. A diagnosis of secondary hemophagocytosis (table 1) complicating a case of pulmonary cryptococcosis was made and was started on dexamethasone 10 mg/m² for 2 weeks after haematology consultation, later tapered over the next 6 weeks. After initiation of corticosteroids, his fever responded. He was switched to oral fluconazole 400 mg/day after 2.25 g cumulative dose of liposomal amphotericin B.

Figure 3.

Giemsa-stained bone marrow aspiration slides showing increased histiocytes with vacuolations, phagocytosed erythrocytes, leucocytes and hemosiderin pigment.

Table 1.

Diagnostic criteria of hemophagocytic lymphohistiocytosis

Diagnostic criteria	Index case
Fever≥38.5°C	Yes
Splenomegaly	Yes
Peripheral blood cytopenias (haemoglobin<90 g/L; platelets <100x109/L; ANC<1000/µL)	Yes
Hypertriglyceridaemia/hypofibrinogenemia	No
Hemophagocytosis in bone marrow, spleen, lymph node or liver	Yes
Ferritin>500 ng/mL	Yes
Elevated soluble CD25	Not done
Low or absent NK cell activity	Not done

ANC, absolute neutrophil count; NK, natural killer.

(Rreproduced from Henter et al)⁶

Outcome and follow-up

After 2 months of antifungal therapy, the patient’s chest radiograph showed resolution of hilar opacity (figure 4). At 6 months of follow-up, the patient is back to his daily routine and is completely asymptomatic.

Figure 4.

(Left) Pretreatment chest radiograph showing right hilar mass with patchy nodular opacities, diffusely distributed, predominantly in the right lung. (Right) Chest radiograph after 8 weeks of therapy showing complete resolution of the opacities and near normal imaging.

Discussion

HLH is a syndrome of uncontrolled immune activation which results in excessive inflammation and tissue damage. The exact incidence is not well known in the adult population. It can be primary (familial) which is usually seen in children or secondary (acquired) which occurs independent of age. Familial HLH is caused by genetic mutations affecting the cytotoxic function of T lymphocytes and natural killer (NK) cells. Secondary HLH occurs in association with infectious, rheumatological, malignant or metabolic conditions. These insults either directly initiate the disease or remain as background illness with increased i risk of hemophagocytosis. HLH secondary to infections occurs most commonly with viral infections (CMV, EBV and herpes simplex virus).^1–3 The association of HLH with fungal infection is less common, occurs most commonly in the setting of AIDS, lymphoma, chronic steroid use and in transplant recipients. Histoplasma species, being the most reported fungi to be associated with HLH,⁴ has been reported in only one case of 12-year-old girl with cryptococcal meningoencephalitis.⁵ In the index case, other causes of hemophagocytosis were reasonably excluded. Hence, we associate the proven pulmonary cryptococcal infection with secondary hemophagocytosis.

The diagnosis of HLH is usually made according to the HLH-2004 trial, either a molecular diagnosis compatible with HLH should be made or five of the eight criteria given in table 1 should be fulfilled.⁶ The diagnosis of our patient was established according to the same criteria as shown in table 1 (five out of eight criteria). The morphological finding of hemophagocytosis is, by itself, neither sufficient nor specific for the diagnosis of HLH.^{6 7} Unlike the other laboratory criteria, it is also not defined quantitatively by the HLH-2004 criteria. A recent study attempting to address this lacuna found that the presence of phagocytosed granulocytes (1/1000 cells) or nucleated erythrocytes (2/1000 cells) or the identification of hemophagocytes with more than one type of nucleated cells is strongly associated with HLH.⁸ All three were present in our case. Bone marrow evaluation is additionally valuable in excluding secondary/acquired causes of HLH, including infections like kala-azar, disseminated cryptococcosis or histoplasmosis, lymphomatous or granulomatous infiltrates and metastatic malignancies.^{1 6 7} Another laboratory-based approach uses reduced level of glycosylated ferritin as an indicator of the hyper-acute rise in ferritin with values≤20% of the normal being strongly predictive of HLH.⁹

The treatment of familial or primary HLH has been systematically studied and reported, and the optimum treatment of secondary HLH remains speculative. Etoposide, dexamethasone and ultimately hematopoietic stem cell transplantation are the mainstay for the majority of patients with primary HLH. Secondary HLH triggered by an acute infection or a rheumatological condition can be appropriately treated with the correction of underlying trigger while secondary HLH due to haematological malignancy requires HLH-specific therapy.⁷ The treatment of the underlying trigger will result in the removal of the stimulus for immune activation. However, patients who are severely ill and deteriorating, in spite of addressing the underlying illness, require prompt initiation of HLH-specific therapy along with supportive management. In our case, the patient was relatively stable having no severe organ dysfunction, and hence chemotherapy was not initiated. However, glucocorticoids were added in view of persistent high-grade fever and fatigue despite 2 weeks of antifungal therapy. Addition of steroids led to resolution of fever and fatigue in the current case.

In summary, HLH in pulmonary cryptococcosis is rare. Early initiation of glucocorticoids in cases which do not respond to treatment of cryptococcosis may result in prompt clinical response avoiding toxic chemotherapy.

Learning points.

• Pulmonary cryptococcosis can be considered as differential even in a case where imaging is suggestive bronchogenic carcinoma.

• Pulmonary cryptococcosis can occur even without frank immunosuppression.

• Hemophagocytic lymphohistiocytosis (HLH) can complicate the course of management of pulmonary cryptococcosis.

• Hemophagocytosis in the bone marrow is by itself insufficient to diagnose HLH. Demonstration of ingested nucleated cells increases specificity.

• HLH secondary to infections may require glucocorticoid therapy in addition to the management of underlying disease.