Microfilaria in achylous hematuria: Can it imitate urolithiasis?

Abstract

Wuchereria bancrofti is the major species resulting in filarial cases in India. Filariasis may present with various clinical presentations: asymptomatic, microfilaremia, lymphedema, acute adenolymphangitis and chronic lymphatic disease. Microfilariae of W. bancrofti have been detected in various clinical samples, but incidental detection of microfilaria in achylous urine is a rare finding with unexplained pathology. We report a case of microfilaria in achylous urine of a 30-year-old female who presented with pain abdomen and ureteric calculus on ultrasonography.

INTRODUCTION

Filariasis is a neglected tropical disease endemic in tropical and subtropical countries, including India where mainly three species cause lymphatic filariasis, namely Wuchereria bancrofti, Brugia malayi, and Brugia timori.[1]

Microfilariae have been detected at various sites by cytology and histopathology.[2,3] However, the presence of microfilariae in urine is rarely seen, which usually is accompanied by chylous urine. However, the presence of microfilariae in normally voided achylous urine is rare. We report a case with microfilariae of W. bancrofti in a 30-year-old female who presented with pain abdomen and achylous urine.

CASE REPORT

A 30-year-old homemaker, native of Uttar Pradesh, was referred to the laboratory from the surgical outpatient department for blood and urine examination. The patient complained of vague abdominal pain for the last 1 year after delivery of her third child. Ultrasonogram of the lower abdomen region had reported evidence of mild hydronephrosis with a 15-mm calculus at the right pelviureteric junction. There was no history of passing milky urine, hematuria, or development of limb swelling or trauma.

Physical examination of the urine revealed clear, pale yellow, achylous urine with no sugar, proteins, or ketones by dipstick test [Figure 1]. Microscopic examination of centrifuged sediment of the urine showed 15–20 pus cells/high power field (hpf), 2–3 epithelial cells/hpf, and 300–400 RBCs/hpf, which were normal in morphology. A single live intact-sheathed microfilaria was seen wriggling under the coverslip [Video 1]. Giemsa-stained smears of the urine revealed microfilariae with intact sheath and absence of nuclei in the cephalic space and pointed tail section which led to a diagnosis of W. bancrofti [Figure 2].

Figure 1.

Pale yellow transparent achylous urine of the patient

Figure 2.

Photomicrographs of urine smears showing microfilariae of Wuchereria bancrofti (Giemsa, ×400)

On a repeat ultrasonogram, no other prepostrenal lesion, venolymphatic or urolymphatic fistulae, or any suspicious focus apart from the existing calculus was seen. Diethylcarbamazine (DEC) provocation test multiple similar live microfilariae were seen under wet mount preparations and were confirmed as W. bancrofti on Giemsa-stained smears.

The patient was referred back to the surgical outpatient department and was started on DEC therapy for 3 weeks before a planned percutaneous nephrolithotomy (PCNL). The patient underwent PCNL subsequently and is now asymptomatic. Samples collected posttherapy with repeat DEC provocation test came out to be negative for both blood and urine microfilariae.

DISCUSSION

Filariasis may present with variable presentations – microfilaremia, lymphedema, hydrocele, acute adenolymphangitis, and chronic lymphatic disease. However, commonly, these infections are asymptomatic.[1,4] Chyluria is seen in only 2% of symptomatic patients in the endemic areas, and achylous hematuria is even more rare, thus making a diagnosis more difficult.[5,6,7]

Our patient presented with pain abdomen with microfilaria in the urine picked up on a routine urine microscopy and a 15-mm calculus at the right pelviureteric junction on ultrasonography. There was no evidence of clinical filariasis such as lymphedema or swelling of lower limbs. However, the patient's pain abdomen subsided after she was started on DEC therapy followed by PCNL. Furthermore, it was not detected in urine afterward. Histopathology of removed stone could not be performed. Subsequently, it was not inferred whether the stone was of filarial etiology or indigenous. The renal involvement in filariasis can cause glomerulonephritis, hematuria, and proteinuria and is associated mainly with microfilaremia.[8]

Our case is unique in presentation as the urine was achylous and microfilaria was incidentally picked up on urine routine microscopy. The other notable finding was microscopic hematuria as urine was clear on gross examination [Figure 1]. Detection of microfilaria in achylous hematuria is unusual with only a few cases documented.[6,9,10] The mechanism of achylous hematuria in lymphatic filariasis is not fully understood, and a lack of significant lymphatic obstruction has been suggested as the reason.[1,11] However, it is difficult in our case to ascertain whether hematuria was due to the presence of the calculus or due to microfilaria. RBCs were normal in morphology ruling out any glomerular pathology due to microfilaria. The possibility of a postglomerular etiology of the kidney stone being filarial in origin to begin with cannot be ruled out. Thus, the enigma remains whether filariasis can cause or mimic nephrolithiasis as it is seen that filariasis can mimic solid tumors.[12]

Detection of microfilariae suggests the presence of adult filarial nematodes in the lymphatics and thus begets treatment. Repeated cytospin preparations from the hematuric and/or chylous urine should be performed at regular intervals for detecting microfilariae in unusual site and presentation in patients from endemic areas if microfilariae are not detected in initial samples.[13]

Apart from routine urine examination and direct demonstration of microfilariae, other investigations which are helpful to diagnose filariasis in case of absence of microfilariae in urine include radiological tests such as ultrasonography and contrast-enhanced computed tomography scan, cystoscopy, intravenous pyelography, lymphangiography, and lymphoscintiography, and immunological tests such as immunoglobulin G4 enzyme-linked immunosorbent assay (ELISA) against W. bancrofti Ag Wb-SXP-1, Og4C3 monoclonal antibody-based ELISA, immunochromatography, antigen-specific immune complexes, indirect fluorescent assay with microfilaria, and filarial DNA by polymerase chain reaction.[1,10] The patient was successfully cured with the drug of choice (DEC, 6 mg/kg daily for 12 days).

CONCLUSION

Most of the asymptomatic patients do not have microfilaremia on presentation. Detection of microfilaria in achylous urine is very rare. However, inexpensive urine microscopy with careful screening can prevent a patient from undergoing expensive and invasive investigations and unnecessary drugs and prevent unnecessary complications.

Informed consent

Informed consent was obtained from the patient for reporting this case in the medical literature.

Declaration of patient consent

The authors certify that they have obtained all appropriate patient consent forms. In the form, the patient has given her consent for her images and other clinical information to be reported in the journal. The patient understands that name and initials will not be published and due efforts will be made to conceal identity, but anonymity cannot be guaranteed.

Financial support and sponsorship

Nil.

Conflicts of interest

There are no conflicts of interest.