Pyoderma Fistulans Sinifica (Fox Den Disease): A Distinctive Soft-Tissue Infection

Abstract

Pyoderma fistulans sinifica (PFS, also referred to as fox den disease because its multiple fistulae and sinuses resemble the structure of a fox den) is a distinct chronic infectious disease in which epithelialized tracts form within the subdermal fatty tissue. PFS, which has not been previously described in the English-language literature, must be differentiated from hidradenitis suppurativa, pilonidal sinus, and perianal fistula. The fistulous tracts of PFS are always lined by stratified squamous-cell epithelium but, unlike those of hidradenitis, reach deep into the subcutaneous fat, run epifascially for long distances, and have no relation to skin appendices. We report on 10 men (mean age +/- SD, 36 +/- 5 years) with PFS (mean duration +/- SD, 11 +/- 7 years). Bacterial cultures of affected tissue from these patients yielded a total of 14 facultative and 31 obligate anaerobic species. Treatment consisted of wide en-bloc excision down to the fascia, including all fistulae. Antibiotic therapy temporarily reduced purulent discharge but did not eradicate the infection. Two patients who underwent fistulotomy without wide en-bloc excision developed recurrences.

Case Report: Mega scrotum in Pyoderma Fistulans Sinifica (Fox Den Disease)

“…The disease affects mainly the lower body, including the buttocks, thighs, lower back, scrotum and perineum of young men [2], as in our case. The anal canal and rectum are always spared, practically elim inating any confusion with complex or neglected perianal fistulas.…”

“…The correct diagnosis hinges on the fact that the fistulous tracts of PFS are always lined by stratified squamous cell epithelium but, unlike those of hidradenitis, burrow deep into the subcutaneous fat, run parallel and superficial to the fascia, and do not involve skin appendices. This diagnosis is often delayed by many years, resulting in numerous unsuccessful surgical procedures [2].…”

“…Careful microbiological studies by Wittmann et al [2] showed that the suppurating subcutaneous tunnels of PFS contain a myriad of facultative but mainly obligate anaerobic species of bacteria. Although long courses of antibiotic therapy may result in transient improvement, antibiotics alone are never curative [2].…”

“…Although long courses of antibiotic therapy may result in transient improvement, antibiotics alone are never curative [2]. Cure can be attained only by the radical excision of the involved soft tissues.…”

“…It is characterized and distinguished from conditions such as hidradenitis suppurativa, pilonidal sinus/cyst or complex fistula-in-ano, by the presence of multiple, deep, epifascial epithelialized tracts, running in parallel and above the fascia-resembling a fox's den [2]. We report a case of extensive PFS causing a mega-scrotum, successfully treated by staged resection.…”