Pseudoactinomycotic Radiate Granules (PAMRAGs) in the Extensor Tendon of Hand

Pseudoactinomycotic radiate granules (PAMRAGs) are most frequently observed in female genitalia. Morphologically, these closely resemble the actual actinomycotic granules. Actinomyces are infectious organisms that require treatment; whereas, PAMRAGs do not require a specific treatment since they are not infectious. Here, we describe a previously unreported case of these granules in the hand. A 56-year woman was admitted with soft mass on the dorsal aspect of her right hand. Peroperatively, lesion was detected in the extensor digitorum communis. Histopathological examination revealed an appearance that resembled actinomyces. Periodic acid-Schiff (PAS) staining was not positive for actinomyces. Hematoxylin-eosin (HE) staining showed radially arranged refractile granules with thick, irregular club-like eosinophilic character without a central core. Thus, actinomycosis was ruled out and a diagnosis of PAMRAGs was made. Differentiating PAMRAGs from actual actinomycotic infections is crucial for the treatment. Pathologists should be familiar with the presence and appearance of PAMRAGs to avoid misdiagnosis of actinomycosis and prevent unnecessary antibiotic use.