Letter to the Editor
Pyoderma gangrenosum with monoclonal IgA gammopathy and pulmonary tuberculosis. Illustrative case and review

Pyoderma gangrenosum (PG) is a non-infectious inflammatory skin disease, resulting in large ulcers that can spread rapidly showing undermined, violaceous borders and a necrotic, purulent base [1–3]. The etiology remains unclear, but it appears to have an immunologic background [2–4]. It is probably a hyperergic reaction, connected with systemic disorders. Neutrophil dysfunction has been suggested (defects in chemotaxis or hyperreactivity). Evidence of abnormal neutrophil trafficking and metabolic oscillations has been described [4]. Circulating immunoglobulins affecting the neutrophil function and monoclonal or polyclonal hyperglobulinemia frequently occur in PG. Evidence suggests disturbances of immunoregulation; immunologic effector dysfunction occurs in some patients [5]. Furthermore, interleukin 8, a potent leukocyte chemotactic agent, is overexpressed in PG ulcers [6].
In up to 70% of cases, PG is associated with a variety of systemic diseases. The most common linkage is to inflammatory bowel disease, such as Crohn’s disease and ulcerative colitis (30%), rheumatoid or psoriatic arthritis (25%), multiple myeloma, hematologic malignancy (particularly leukemia and monoclonal gammopathies), paraproteinemia (particularly IgA), viral hepatitis, diverticulitis, non hematological malignancy – prostate and renal adenocarcinoma, stomach carcinoid, and Kaposi’s sarcoma [4, 7, 8]. There is also a rare familial form of PG, PAPA syndrome (pyogenic sterile arthritis, PG and acne), an autosomal dominant disorder resulting from a PSTPIP1 gene mutation [6]. Another syndrome with PG is PASH (PG, acne and suppurative hidradenitis) [4].
The distinctive clinical features of PG are often sufficient to establish the diagnosis. However, diagnostic criteria have been articulated which require two major criteria and at least two minor criteria [4]. Major criteria: 1) Rapid progression of a painful, necrolytic, cutaneous ulcer, with an irregular, violaceous and undermined border, margin expansion of 1 to 2 cm per day or a 50% increase in ulcer size within 1 month. Pain is usually out of proportion to the size of the ulceration, typically preceded by a papule, pustule or bulla. 2) Other causes of cutaneous ulceration have been excluded – usually this necessitates skin biopsy or other investigations. Minor criteria: 1) History suggestive of pathergy or clinical finding of cribriform scarring. 2) Systemic diseases associated with PG. 3) Histopathologic findings...


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