Rapidly Progressive Malignant Pelvic Perivascular Epithelioid Cell Neoplasm (PEComa) Associated with Eggerthella lenta Bloodstream Infection

Abstract

Perivascular epithelioid cell tumors (PEComa) are rare mesenchymal neoplasms composed of cells that express melanocytic and myogenic markers and grow around small blood vessels. PEComa often show benign behaviors but can also be highly aggressive. In frail and more complex patients, many conditions can overlap, compounding the diagnostic and therapeutic difficulties inherent in rare diseases. Moreover, the complexity of modern patients introduces new and significant players in host-microbe interactions, and emerging pathogens represent a relevant challenge to modern healthcare. Among these pathogens is Eggerthella lenta, an anaerobic gram-positive bacterium of the normal gut microbiota associated with life-threatening infections. Here, we present a case of malignant pelvic PEComa with rapid metastatic progression in a 73-year-old man who presented with an E. lenta bloodstream infection. Approaching differential diagnosis with open-mindedness may assist in better imaging interpretation, surgery scheduling, and proper treatment planning. The non-specific clinical presentation might delay timely diagnosis, while the absence of well-consolidated guidelines undermines the accurate management of the disease, for which strict follow-up can favor better outcomes. Progress in diagnostic techniques, such as the implementation of MALDI-TOF (matrix-assisted laser desorption/ionization-time of flight) mass spectrometry for micro-organism identification, helps with a more accurate pathogen diagnosis and characterization. This allows the implementation of the most appropriate therapy, as well as better surveillance of antibiotic resistance, infection prevention, and control measures. Nevertheless, a good dose of wisdom is vital to avoid overlooking potentially harmful pathogens, particularly in frail individuals.

Keywords: Bloodstream infection; Eggerthella lenta; Emerging pathogens; Intra-abdominal abscess; Malignant perivascular epithelioid cell tumor; PEComa.

Fig. 1.

Computed tomography-urography showed a coarse expansive neoformative lesion in the central portion of the pelvis, approximately 10 cm×10 cm×11 cm in size, with a non-homogeneous structure that was partly solid and partly colliquated.

Fig. 2.

Pelvic magnetic resonance imaging showed a coarse expansive neoformative lesion in the central portion of the pelvis, approximately 10 cm×10 cm×11 cm in size, with a non-homogeneous structure that was partly solid and partly colliquated.

Fig. 3.

(A) Histopathological evaluation showed a lesion composed of high-grade epithelioid cells with clear to eosinophilic and granular cytoplasm (original magnification ×10); necrosis and brisk mitotic activity were reported. (B) The cells were positive for cathepsin-K (original magnification ×20), melanocytic and smooth muscle markers.