Mycotic cysts: report of 21 cases including eight pheomycotic cysts from Saudi Arabia.
BACKGROUND
Mycotic cysts are subcutaneous cystic granulomas caused by either dematiaceous (pigmented) fungi (pheomycotic cysts) or eumycotic (nonpigmented fungi) present in soil, wood, and decaying plant material. These fungi gain access to the tissues via a wooden splinter or thorn. No deep tissue involvement or extension to bone is known to occur.


METHODS
We reviewed our surgical pathology files for the last 32 years. All cases with the diagnosis of cysts with fungi, thorns, or splinters and associated granulomatous and acute inflammation were reviewed. Gomori's silver and periodic acid-Schiff stains were performed in all cases.


RESULTS
Twenty-one cases of mycotic cyst were found, including eight pheomycotic cysts (one with a recurrent lesion seen 11 months after the initial excision of the cyst). Thirteen cysts had nonpigmented fungal hyphae. There were 14 males and seven females, with an age range of 5-76 years. The dorsum of the foot was the most frequently affected site (12 cases). Four cases involved the fingers, two involved the knee area, two involved the big toe, and one each involved the leg, ankle, and forearm. The cysts measured 0.6-4.5 cm in diameter. Histologically, there was granulomatous inflammation with a variable degree of neutrophilic infiltrate giving central abscess formation. Twelve cases showed a wooden splinter. All cases were positive for fungal organisms, mostly septate hyphae and spores that were highlighted by special stains. Fungal pigment, ranging from yellow-brown to light brown to black, was observed in eight cases. No extension to deep tissues was noted. The clinical impression varied widely including ganglion, sebaceous cyst, giant cell tumor of the tendon sheath, and lipoma. One patient was immunosuppressed following renal transplantation. All patients were treated by simple excision. No antifungal chemotherapy was needed or administered in any of the patients. One patient had a recurrence of his lesion within 1 year as a result of inadequate initial excision. A second re-excision was curative.


CONCLUSIONS
Mycotic cysts are uncommonly encountered lesions that can be easily missed, especially in cases with scant fungal elements, thus requiring special stains to detect the organisms. We reported 21 cases of mycotic cyst, including eight pheomycotic cysts, with emphasis on the histopathologic recognition of this unusual entity.
Sheikh
Salwa S
SS
Pathology Services Division, Dhahran Health Center, Dhahran, Saudi Arabia. sheikhss@aramco.com.sa
Amr
Samir S
SS
D000293:Adolescent; D000328:Adult; D000368:Aged; D002675:Child, Preschool; D003881:Dermatomycoses / Q000453:epidemiology* / Q000209:etiology / Q000473:pathology / Q000601:surgery; D004814:Epidermal Cyst / Q000453:epidemiology* / Q000209:etiology / Q000473:pathology / Q000601:surgery; D005260:Female; D005385:Fingers; D005528:Foot; D006801:Humans; D007866:Leg; D008297:Male; D008499:Medical Records; D008875:Middle Aged; D012189:Retrospective Studies; D012529:Saudi Arabia / Q000453:epidemiology