Role of [ 18 F]Fluorodeoxyglucose Positron Emission Tomography-Computed Tomography for Diagnosis and Treatment of Sarcoidosis in an HIV-2-Infected Patient

A 42-year-old African woman with HIV-2 infection since 2002 came to the outpatient infectious diseases clinic for persistent fever, cough, night sweats and a 20-kg weight loss over a 12-month period. Concomitantly, her absolute and percentage CD4 T cell count declined from 450/mm³ (30%) to 218/mm³ (18%), although HIV-2 viral suppression (<50 copies/ml) and optimal intake of raltegravir 400 mg BID and lopinavir/ritonavir 400/100 BID. Her physical examination and vital signs were normal; her body temperature was 37.4°C. Both a mycobacterial examination of her sputum smear (culture, microscopy, and PCR testing) and a QuantiFERON test produced negative results, but a chest radiograph revealed increased opacity in the right lower lobe.

After 14 days of unsuccessful empirical antibacterial therapy she was hospitalized. A computed tomography (CT) scan showed multiple bilateral ground glass opacities and enlarged mediastinal and pulmonary hilar lymph nodes. We performed several invasive diagnostic procedures that were negative for Mycobacterium tuberculosis and other infectious agents [bronchoalveolar lavage (BAL), cerebrospinal fluid, and lymph node biopsy].

The lymphoid population on the BAL sample consisted mainly of CD3⁺ T cells, with a CD4/CD8 ratio of 5.6. The transbronchial biopsy showed inflammatory lymph granulocytic infiltrates. The mediastinal lymph node transbronchial needle aspiration revealed sparse histiocytes without epithelioid cell granulomas. Finally, the mediastinal lymph node biopsy showed necrosis with confluent granulomas without acid-fast bacilli. Concomitantly, the patient developed interstitial nephritis with renal impairment without hypercalciuria and/or hypercalcemia.

Consistent with the presence of two major diagnostic criteria (noncaseating granulomas and lack of acid-fast bacilli on biopsy) ¹ and a CD4/CD8 ratio greater than 4:1 on BAL, ² we diagnosed a multisystemic sarcoidosis. A baseline [¹⁸F]fluorodeoxyglucose positron emission tomography-computed tomography (¹⁸FDG-PET/TC) showed intense FDG uptake in several lymph node stations on both sides of the diaphragm (Fig. 1A). High-dose prednisone (1 mg/kg/daily) was then started with rapid clinical improvement and weight gain; after a few weeks, steroid treatment was slowly tapered to 7.5 mg/daily. Five months later, a second ¹⁸FDG-PET/TC revealed partial resolution of the nodal disease; tissue-specific glucose uptake semiquantitative analysis revealed a partial metabolic response. Conversely, splenic uptake was inhomogeneously increased (Fig. 1B). The prednisone dosage was then increased to 50 mg/day and subsequently tapered off slowly to 10 mg/day. A third ¹⁸FDG-PET/TC, performed 10 months after the start of prednisone, showed a complete metabolic response in all tissues (Fig. 1C). At the same time, the CD4 T cell count rose to 389/mm³ (23.6%). Renal function remained stable, although altered.

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FIG. 1.

(A) [¹⁸F]Fluorodeoxyglucose positron emission tomography-computed tomography (¹⁸FDG-PET/TC) shows very intense FDG uptake in several lymph node stations on both sides of the diaphragm. This uptake pattern is compatible with a lymph-proliferative disorder. (B) The examination, executed during corticosteroid treatment, shows partial resolution of the nodal tracer uptake. Notably, the glucose analogue distribution is markedly augmented within the spleen. (C) Ten months after the beginning of steroid therapy, ¹⁸FDG-PET/TC shows complete resolution of the nodal and splenic involvement, supporting the hypothesis of inflammatory granulomatous disease.

Granulomatous disease in HIV-infected patients needs a multidisciplinary approach and nuclear medicine could be a valid support. ³ Sarcoidosis is rare in HIV; no diagnostic criteria are tailored in this setting and this make the diagnosis challenging. To our knowledge, only one case of sarcoidosis had previously been reported in HIV-2 infection. ⁴ Moreover, starting high-dose steroid treatment in the presence of HIV infection and a low CD4 T cell count is a cause for concern. Longitudinal assessment of serial ¹⁸FDG-PET/TC is a valuable imaging tool in assessing treatment efficacy, especially in the case of extrapulmonary unusual features such as diffuse FDG splenic uptake.