How is filariasis in the breast diagnosed?

Diagnosis of Breast Filariasis

Breast filariasis is diagnosed definitively by real-time ultrasound demonstrating the pathognomonic "filarial dance sign"—vigorous twirling movement of multiple curvilinear echoes within a cystic lesion—which allows immediate treatment initiation without invasive procedures in endemic areas. 1, 2

Primary Diagnostic Approach

Real-Time Ultrasound (First-Line in Endemic Areas)

• Perform real-time sonographic examination to identify the characteristic "filarial dance sign," which appears as vigorous twirling movement of multiple curvilinear echoes within cystic lesions 1, 2
• Look for mixed red-blue color Doppler signals that are non-rhythmic, non-pulsatile, with irregular pulse Doppler traces due to worm movement 2
• This finding is pathognomonic and sufficient to initiate treatment without delay, avoiding unnecessary biopsies 1, 2

Clinical Presentation to Recognize

• Painless or tender palpable breast nodule that clinically mimics fibroadenoma or fibroadenosis 3, 4
• Duration typically one month or less at presentation 4
• Most commonly affects upper quadrants of the breast 1
• Patient history from endemic areas (tropical countries, particularly Indian subcontinent) 3, 5

Secondary Diagnostic Methods

Mammography Findings

• Well-defined lobulated density on mammogram, resembling benign lesions 1
• Calcified serpiginous structures representing dead calcified worms in chronic cases—these show typical linear or curvilinear calcifications 5
• Mammography alone is insufficient for diagnosis but may suggest the diagnosis when calcifications are present 5

Fine Needle Aspiration Cytology (FNAC)

• Reveals adult gravid filarial worms with numerous microfilariae and granulomatous inflammatory response 3
• Shows predominantly chronic inflammatory cells in many cases 4
• Use FNAC when ultrasound is unavailable or when the filarial dance sign is not demonstrated 3

Histopathological Examination

• Excisional biopsy shows adult worms with surrounding granuloma in tissue sections 4
• Reserve for cases where diagnosis remains uncertain after ultrasound and FNAC, or when malignancy cannot be excluded 4
• Demonstrates host granulomatous response around the parasite 3, 4

Critical Diagnostic Algorithm

Step 1: In any patient from endemic areas presenting with a breast lump, perform real-time ultrasound first 1, 2

Step 2: If filarial dance sign is present, diagnose breast filariasis and initiate treatment immediately with diethylcarbamazine, albendazole, and antibiotics 3

Step 3: If ultrasound is negative but clinical suspicion remains high (endemic area, unexplained granulomatous features), proceed to FNAC 3

Step 4: If FNAC shows microfilariae or adult worms, confirm diagnosis and treat 3

Step 5: Only perform excisional biopsy if diagnosis remains uncertain and malignancy cannot be excluded by standard breast cancer diagnostic triad 6, 7

Important Clinical Pitfalls

• Do not assume fibroadenoma without ultrasound in endemic areas, as clinical and mammographic features overlap significantly 1
• Unexplained granulomatous breast lesions should prompt consideration of filariasis in patients from endemic regions 3
• The presence of calcifications on mammography may represent chronic filarial infection rather than malignancy 5
• Chronic inflammatory cells on FNAC without specific diagnosis warrant further investigation for parasitic etiology 4