Unusual clinical manifestation of a disfiguring necrobiotic granulomatous disease

An Unusual Cause of Refractive Chronic Bilateral Leg Ulceration

Background:

Ulceration of the lower extremities is a common disorder that can be very painful. It occurs most frequently in the elderly population as a result of venous hypertension. We report an unusual case of a 32-year-old man with an 11-year history of extensive, painful, bilateral leg ulcers resistant to conventional treatment necessitating above-knee amputation of the left leg. Eventually, the patient was treated with prednisone, which led to almost complete healing of the ulcers of the right leg.

Objective:

The objective of this report is to discuss a rare cause of chronic bilateral leg ulceration.

Methods:

Detailed histopathologic examination showed a complex pattern of overlapping features of several specific dermatologic conditions, including necrobiosis lipoidica (NL), necrobiotic xanthogranuloma (NXG), and the destructive form of granuloma annulare (GA).

Conclusion:

The characteristics of our patient suggest a variant of a cutaneous necrobiotic disorder that has not been previously reported. When clinicians are confronted with recalcitrant ulcerations in the lower extremity, this group of disorders should be considered in the differential diagnosis.

An unusual cause of refractive chronic bilateral leg ulceration

BACKGROUND

Ulceration of the lower extremities is a common disorder that can be very painful. It occurs most frequently in the elderly population as a result of venous hypertension. We report an unusual case of a 32-year-old man with an 11-year history of extensive, painful, bilateral leg ulcers resistant to conventional treatment necessitating above-knee amputation of the left leg. Eventually, the patient was treated with prednisone, which led to almost complete healing of the ulcers of the right leg.

OBJECTIVE

The objective of this report is to discuss a rare cause of chronic bilateral leg ulceration.

METHODS

Detailed histopathologic examination showed a complex pattern of overlapping features of several specific dermatologic conditions, including necrobiosis lipoidica (NL), necrobiotic xanthogranuloma (NXG), and the destructive form of granuloma annulare (GA).

CONCLUSION

The characteristics of our patient suggest a variant of a cutaneous necrobiotic disorder that has not been previously reported. When clinicians are confronted with recalcitrant ulcerations in the lower extremity, this group of disorders should be considered in the differential diagnosis.

Asymptomatic deficiency in the peptide transporter associated to antigen processing (TAP)

Human HLA class I deficiency is a rare disease which, in most of the patients described to date, results from a defect in subunit 1 or 2 of the peptide transporter associated with antigen processing (TAP). The clinical features of TAP deficiency include a chronic inflammation of the respiratory tract and/or granulomatous skin lesions. In this report, we describe two adult siblings with an HLA class I deficiency. One individual had only spontaneously-healing skin granulomatous lesions, while the second did not display any of the symptoms associated with HLA class I deficiency and could be considered to be healthy. We show that the patients display a homozygous TAP2 mutation which blocks the maturation of HLA class I molecules. Cell surface expression of these molecules is strongly reduced, but three times higher than on cells from other previously described TAP-deficient individuals. This higher expression results, at least in part, from the presence of HLA-B7 molecules which are probably empty of peptide. The numbers of CD8+ alphabeta T cells are almost normal in these patients. The anti-EBV T-cell response of one patient is mediated by HLA-B7 restricted CD8+ alphabeta T lymphocytes recognizing the BMRF1 nuclear EBV antigen, demonstrating that CD8+ alphabeta T cells can participate in anti-viral responses. This study shows that TAP deficiency can remain totally asymptomatic for several decades, and suggests that in some cases, TAP-independent immune responses provide efficient protection from most of the common intracellular pathogens.

Association of a syndrome resembling Wegener's granulomatosis with low surface expression of HLA class-I molecules

BACKGROUND

Granulomatous syndromes, such as Wegener's granulomatosis, are defined according to complex criteria, but the underlying cause is rarely identified. We present evidence for a new aetiology for chronic granulomatous lesions associated with a recessive genetic defect, which is linked to the human leucocyte antigen (HLA) locus.

METHODS

Five adults with necrotising granulomatous lesions in the upper respiratory tract and skin, associated with recurrent bacterial respiratory infections and skin vasculitis, were identified. A diagnosis of Wegener's granulomatosis was considered in all of them, but abandoned because of an incompatible disease course and resistance to immunosuppressive treatments. Peripheral-blood samples were taken and analysed by immunohistochemistry and fluorescent-activated-cell-sorter analysis. Since all five patients were homozygous for the HLA locus, we looked for genetic defects located within the HLA-locus with PCR and restriction fragment length polymorphism.

FINDINGS

A severe decrease in cell-surface expression of HLA class-I molecule was seen in all patients. Defective expression of the transporter associated with antigen presentation (TAP) genes was responsible for the HLA class-I down-regulation, and in two patients we identified a mutation in the TAP2 gene responsible for the defective expression of the TAP complex. We showed the presence of autoreactive natural killer (NK) cells and gammadelta T lymphocytes in the peripheral blood cells of two patients. Correction of the genetic defect in vitro restored normal expression of HLA class-I molecules and prevented self-reactivity in the patients' cells. Histology of granulomatous lesions showed the presence of a large proportion of activated NK cells.

INTERPRETATION

Our findings define the cause and pathogenesis of a new syndrome that affects patients with a defective surface expression of HLA class-I molecules. The syndrome resembles Wegener's granulomatosis both clinically and histologically. Patients have chronic necrotising granulomatous lesions in the upper respiratory tract and skin, recurrent infections of the respiratory tract, and skin vasculitis. A predominant NK population within the granulomatous lesions suggests that the pathophysiology of the skin lesions may relate to the inability of HLA class-I molecules to turn off NK cell responses. Accurate genetic analysis of a defined syndrome can provide a better understanding of the cause and pathogenesis of a disease.