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Is this rapidly enlarging facial lesion caused by an infection, or something more obscure? That's the diagnostic puzzle when a woman in her late 70s presented with a tender, draining, purplish facial plaque. Brandon Adler, MD, and co-authors at the Keck School of Medicine at the University of Southern California in Los Angeles, reported the case in .

On physical examination, they noted a 3 × 4 cm violaceous plaque with focal purulent drainage on the left side of the patient's nose and adjacent cheek. The patient noted that she had already received several courses of antibiotic treatment, with no effect on the abscess. Her medical history included immunoglobulin A monoclonal gammopathy of unknown significance.

She told clinicians that she had been to Kenya for an extended visit a few years previously. The patient had no fever, night sweats, difficulty breathing, or headaches, and had not lost weight, had no changes to her vision, and did not have any joint stiffness.

At a subsequent appointment about 6 weeks later, the lesion had expanded significantly to involve both cheeks, the forehead, and the area of skin between her eyebrows, and had become a vegetative, freely draining plaque.

Findings of a CT scan suggested that the infection did not extend to the orbits, sinuses, or bone, and chest x-ray indicated nothing of note. Tissue culture at 2 weeks and a QuantiFERON-TB Gold test result were both negative.

Further testing provided little additional information.

"Biopsies showed infected, granulomatous dermatitis with an unremarkable epidermis; findings of a stain results were negative," Adler and co-authors wrote. "An extensive infectious workup, including final tissue cultures/polymerase chain reactions and serology, yielded negative results. Autoimmune markers, including antineutrophil cytoplasmic antibodies, were negative."

Findings from the ophthalmologic exam were also unremarkable. Results of infectious-agent testing had yet to be returned. Given that the condition had not responded to previous treatment with high-potency topical and intralesional corticosteroids, clinicians arrived at a presumptive diagnosis of pyoderma gangrenosum (PG).

Following treatment with prednisone 0.5 mg/kg per day, new crusted plaques developed on the patient's scalp, and a dusky bulla emerged on her left shin, which progressed into an ulcer with undermined borders. Adler and co-authors reported that a biopsy of the shin ulcer revealed "neutrophil-rich dermatitis with secondary vasculitic changes, further supporting the PG diagnosis."

The team increased prednisone to 1 mg/kg per day, which stopped the growth and resolved the drainage. The next step was infliximab (Remicade), colchicine, and tacrolimus ointment to wean the patient gradually from steroids. At the 8-month follow-up, the abscess had continued to improve, although considerable facial cribriform scarring remained.

Discussion

Clinicians reporting this case of a patient with a rapidly progressing facial abscess observed that PG on the head and neck is often considered rare, but actually may just be under-recognized. The patient's facial lesions presented with features that suggested superficial granulomatous PG (SGPG), "an uncommon PG subtype that presents with vegetative or ulcerative lesions and may involve the face, particularly the cheeks," the authors wrote.

However, several features of this case were uncharacteristic of SGPG, which is typically slow to progress and has the potential to resolve on its own. "The present case exhibited rapid progression with impending ocular compromise" and required systemic immunosuppression for remission, the authors said.

Histologically, SGPG presents as a three-layer "granuloma (a central layer of neutrophils and necrosis surrounded by histiocytes and then an outer layer of plasma cells and eosinophils), although suppurative and granulomatous dermatitis is also characteristic of this entity," Adler and co-authors explained.

In their patient, initial vegetative/suppurative facial lesion occurred before a more typical bullous/ulcerative lesion developed in another location -- specifically the shin. These features seem to suggest that SGPG is a variant of PG rather than a separate condition that has been proposed to be called "superficial granulomatous pyoderma."

Complications reported by a of 170 cases of head and neck PG -- with just eight cases of SGPG -- included scarring/disfigurement (48%), local structure invasion (29%), and eye involvement (8%). PG was considered a diagnosis of exclusion until the validation of the following 2018 carrying a sensitivity and specificity for ulcerative PG of 86% and 90%, respectively.

The major criterion was biopsy of the ulcer edge demonstrating neutrophilic infiltrate and the following eight minor criteria:

• Exclusion of infection

• Pathergy

• History of inflammatory bowel disease or inflammatory arthritis

• History of papule, pustule, or vesicle ulcerating within 4 days of appearing

• Peripheral erythema, undermining border, and tenderness at the ulceration site

• Multiple ulcerations, with at least one on an anterior lower leg

• Cribriform or "wrinkled paper" scarring at healed ulcer sites

• Decreased ulcer size within 1 month of initiating immunosuppressive medication

The case authors pointed out, however, that these are most relevant to ulcerative PG and apply less to other variants. The presence of immunoglobulin A monoclonal gammopathy of unknown significance, a known PG comorbidity, was helpful in diagnosing this particular case. The team cautioned though that PG cannot be diagnosed based on histological evidence of suppurative granulomas until an infection has been ruled out using infectious stains and tissue cultures, which may have differing sensitivities.

The authors noted that because this patient had visited Kenya, where tuberculosis is endemic, it was important to consider potential infection with lupus vulgaris. People with intact cell-mediated immunity can develop this form of , which causes red-brown papules typically affecting the face.

"Histology displays variable tuberculoid or sarcoidal granulomas, usually lacking suppuration or caseation necrosis," Adler and co-authors wrote. "While it is uncommon to visualize acid-fast bacilli on , tissue cultures and/or polymerase chain reaction test results may be positive. Purified protein derivative skin test and interferon γ release assay are usually positive in lupus vulgaris."

Authors of a small and review of superficial granulomatous PG involving the face observed that facial presentation is very rare, accounting for only 9% of 46 cases of granulomatous PG, while 52% of lesions were located on the trunk, 31% on the extremities, 5% in the groin, and 2% on the scalp.

Another differential diagnosis to consider in a patient from California presenting with suppurative granulomas, Adler and co-authors noted, is disseminated cutaneous coccidioidomycosis (Valley fever), caused by the spore-forming fungus Coccidioides immitis, which is common in the Southwestern U.S.

While histology findings consistently show granulomatous inflammation, the pattern of inflammation varies from suppurative/granulomatous to less common lymphoplasmacytic, sarcoidal, neutrophilic, necrotizing, or eosinophilic patterns. These organisms appear as endospore-filled spherules ranging from 5 to 75 μm in diameter. Tissue, serologic, and imaging studies can help exclude this diagnosis.

Histological analysis may also show secondary vasculitic changes in cases of PG and other neutrophilic dermatoses. Concurrent granulomas and vasculitis can also suggest "granulomatosis with polyangiitis, a small-/medium-vessel vasculitis associated with upper/lower respiratory and kidney complications," the case authors noted. However, this condition can present atypically, with PG-/SGPG-like lesions sometimes referred to as malignant pyoderma. This diagnosis was excluded in this patient's case, given that there was no systemic involvement or evidence of antineutrophil cytoplasmic antibodies.

"Superficial granulomatous PG is a challenging diagnosis requiring a comprehensive workup to rule out mimickers, particularly infections; however, this must be balanced with the need for prompt initiation of immunosuppression in more aggressive cases involving the face that can eventuate in permanent disfigurement," the authors concluded.

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