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Amer et al. Metastatic myonecrosis

Table 1: Underlying conditions in nontraumatic clostridial I. Traumatic:
gangrene [8]
Gastrointestinal factors A. Simple contamination (no clinical evidence of
Colon tumor sepsis)
Ulceration of mucosa
Chemotherapy B. Anaerobic cellulitis (local gas gangrene, with
Radiation healthy muscle not invaded, e.g. pressure sores,
Instrumentaion
Bowel infarction diabetic foot ulcer)
Intestinal surgery C. Anaerobic myonecrosis (classical, with invasion of
Diverticulitis
Necrotizing enterocolitis living muscle)
Ileitis or colitis
Fecal impaction [9,11]
Intussusception II. Nontraumatic or idiopathic (typically arising from
Volvulus visceral intra-abdominal catastrophes, such as
Straining at stool
Systemic factors perforated cecal cancer)
Leukemia
Lymphoproliferative disorder A. Anaerobic cellulitis
Diabetes mellitus
Metastatic tumor (nongastrointestinal) with chemotherapy B. Contiguous myonecrosis
Neutropenia C. Metastatic myonecrosis
Cirrhosis

or cyclic neutropenia. Presumably, the anaerobic Clinical course
[5]
glycolysis and the acidic milieu within a tumor provide Gas gangrene is a rapidly spreading infection. It can
[7]
a favorable environment for the germination of the advance as fast as 2 cm per hour. The incubation
[1]
clostridial spores. The affinity for necrotic tissue is not period varies from 6 h to 2 days. The bacilli produce
[5]
specific for malignant tissue only, as demonstrated by several exotoxins, which can destroy the host tissue
Thiele et al. where spores of Clostridia were injected and increase permeability. The resultant necrosis,
[5]
in necrotic tissue other than tumor and were found to edema, and ischemia favor clostridial reproduction in
germinate. This study may explain the predilection of which more toxins are released, and a cycle ensues.
C. septicum for patients with necrotic colon cancer,
spontaneous bowel perforation, chemotherapy Carbon dioxide and hydrogen are liberated during
treatment, surgery, or medical procedure such as the process, which opens fascial planes and
endoscopy or barium enema. Once established, C. facilitates spread. The pathogenesis of subcutaneous
septicum may either cause a locally invasive infection emphysema from disruption of the gastrointestinal
[12]
or spread via the bloodstream to distant skeletal tract depends on localized bowel wall weakness,
muscle (causing myonecrosis) or to other organs the anatomic site, and an increased pressure gradient
[4]
(producing abscesses that may be indistinguishable between the bowel lumen and extramural tissue. The
from metastasis). Clostridial organisms produce perforation occurs at a point of weakness in the bowel
[3]
wall where vigorous peristaltic movement produces
toxins that are responsible for the rapid spread and a large pressure gradient, precipitating rupture of
systematic toxicity of these infections. C. septicum the disease site. When subcutaneous emphysema
[3]
is believed to produce four toxins, one of which is occurs, it is usually confined to the anterior abdominal
hemolysin, which is oxygen stable. In addition, it also wall. From there it passes to the lower extremity via
produces a deoxyribonuclease, a hyalurinidase, and the femoral canal or along the iliopsoas muscle to
oxygen labile hemolysins. Secondary toxicity may its insertion into the lesser trochanter of the femur.
result from the products of tissue breakdown such The gas then spreads freely along the fascial planes
as creatinine phosphokinase (CPK). Diabetics, [5,6,9] towards the knee.
[3]
on the other hand, seem susceptible to developing
spontaneous gas gangrene. This is most likely due The two main types of gas-forming inflammatory
to their propensity to develop focal tissue ischemia processes [11,13] are:
and acidosis secondary to atherosclerosis and
microangiopathic vascular disease, which allow the 1. Emphysematous cellulitis; accounts for the vast
circulating Clostridia organism to propagate in the majority of gas-forming infection in hospital
hypoxic area. On the other hand, suppurative infection practice.
without signs of myonecrosis or toxemia is the most 2. Emphysematous myositis (gas gangrene).
common form of clostridial disease. [5]
Patients usually complain of severe pain,
[2]
The following is a histotoxic classification of gas disproportionate pain, [3,6,14] and sometimes describe
gangrene (based on MacLennan’s monograph): [5] the sensation as “heavy”. [3,15] Patients are usually
404 Journal of Cancer Metastasis and Treatment ¦ Volume 2 ¦ October 21, 2016