Cutaneous granulomatous inflammation

A granulomatous inflammatory reaction pattern in the skin is common. There can be diverse morphological appearances histologically and numerous aetiologies. The principal reaction patterns are those of epithelioid (sarcoidal and tuberculoid) granulomas, palisaded granulomas, suppurative granulomas, xanthogranulomas, foreign body granulomas and miscellaneous granulomatous conditions. Traditionally, the granulomatous reaction pattern is considered to be a benign/reactive phenomenon. However, a number of malignancies can mimic benign granulomatous inflammation. Rational classification of cutaneous granulomatous inflammation is therefore difficult and at best imperfect since there is an overlap between the histological patterns. As with all inflammatory dermatoses, clinicopathological correlation is essential. Additionally, special techniques and molecular pathology may be required. However in a minority of cases it will not be possible to make a definitive diagnosis, even with all the clinical information available.