Review of Answer Choices (Correct Answer in Green):
A. Ecthyma gangrenosum – a vessel invasive disease, classically caused by Pseudomonas aeruginosa.
B. Pyoderma gangrenosum – classically presents as an ulcer with a violaceous, undermined border in a patient with underlying systemic disease.
C. Vasculitis – always presents with palpable purpura and ulceration
D. Squamous Cell Carcinoma – lesion characteristics depend on the degree of differentiation of the tumor, with well-differentiated tumors presenting as firm or indurated plaques, papules or nodules, whereas poorly differentiated tumors may resemble pyoderma gangrenosum, with a fleshy appearance, and possible ulceration and necrosis.
Explanation:
A. Ecthyma gangrenosum: Vessel invasive disease, classically caused by Pseudomonas aeruginosa. Bacteria proliferate and infiltrate the adventitia, media and perivascular regions of subcutaneous blood vessels, eventually leading to vessel occlusion as bacteria proliferate. This syndrome presents as painless, erythematous macules, and progresses into purpuric lesions with eschar. These lesions may be bullous or pustular and may have branched features.
B. Pyoderma gangrenosum (PG): A common neutrophilic autoinflammatory disease that classically presents as an ulcer, but clinical variants include bullous, pustular, superficial granulomatous, and pyostomatitis vegetans. The classic PG ulcer has a violaceous, undermined borders. It heals with scarring and with a characteristic cribriform or criss-cross pattern. PG is a chronic, recurrent disease that is frequently associated with systemic disease. PG often presents in patients with underlying systemic disease, most commonly IBD, inflammatory arthritis, or hematologic disease or malignancy.
C. Vasculitis: Cutaneous findings depend on the size of the vessel involved. Small vessel vasculitis classically presents with palpable or macular purpura, whereas medium to large vessel involvement may present with ulcers, subcutaneous nodules, and/or necrosis of the digits. Typically, if there are ulcers this indicates involvement of deeper vessels.
D. Squamous Cell Carcinoma: Most commonly arises on areas exposed to sun in fair-skinned individuals (i.e. face, neck, extremities), but on areas not exposed in individuals with dark skin (i.e. lower legs, anogenital region). In patients whose ulcer(s) is not healing as predicted, a biopsy may be necessary to rule out skin cancer. Ulceration is more commonly seen in poorly differentiated invasive tumors.
Images:
Ecthyma gangrenosum:
Pyoderma gangrenosum:
Squamous Cell Carcinoma:
