Table 1 Clinical stages of pyomyositis [1–3, 5, 6, 8–11]
From: Pyomyositis is not only a tropical pathology: a case series
Stage 1 | Invasive | About 2% of patients present in this stage. This stage lasts from 10 to 21 days. Insidious onset of dull, cramping pain, a low-grade fever, muscle ache, general malaise, and anorexia. There is localized edema, sometimes described as indurated or woody, with little or no tenderness. There is no abscess, and examination of aspiration specimens is unrevealing. |
Stage 2 | Purulent or suppurative | About 90% of patients present in this stage. In one study, the mean duration of symptoms before hospitalization was 24 days, whereas in other studies it was respectively 12 days and 6.2 days. Fever and chills. This phase is characterized by abscess formation. Pathologic findings on biopsy show edematous muscle fibers, lymphocytic infiltration, and suppuration as the muscle belly is replaced by pus. The involved muscle is usually tender and the overlying skin may be normal or mild eruptive. |
Stage 3 | Late stage | High fever, severe pain, local signs of infection and systemic manifestations of sepsis may be present. The final stage is characterized by septicemia, metastatic abscesses, and multi-organ dysfunction, and is associated with high mortality. There is exquisite tenderness of the involved area. |