Acne conglobata is a chronic and severe form of acne vulgaris characterized by burrowing abscesses and irregular scarring. The lesions may  be associated with sinuses,  necrosis and  granulomatous  inflammation. Males are more affected than females and the onset is usually  between the ages of 18 and 30 years.  Acne conglobata may develop by the sudden deterioration of existing active papular  or pustular  acne or may be  the recrudescence of acne  quiescent for  many years. The precise cause of acne conglobata is unknown; changes in reactivity to Propionibacterium acnes may be  important.

Blackheads are a conspicuous feature and classically they appear in pairs or groups on the neck or trunk. Indeed they may even extend to involve the upper arms or buttocks. Inflammatory nodules  form,  usually in relation to multiple comedones, gradually increasing in size  and  breaking  down to discharge pus.  As  the nodules break down, crusts may  form   over an indolent deep ulcer which extends centrifugally the antigen  patterns of acne conglobata patients was observed. Treatment Because of the extent and severity of acne conglobata, patients should  be offered isotretinoin. If it  is  not available,  high  doses of tetracycline or erythromycin (1.5 g/day) should be given, plus topical therapies such as alternate use of retinoic acid and benzoyl peroxide. Physical  extraction of comedones will help, as will intralesional injection of triamcinolone into  the larger inflamed cysts.

  A  very  rare  complication  of acne  conglobata is squamous cell carcinoma. Of six members in one family with acne conglobata, two developed large,  aggressive and well-differentiated squamous cell carcinomas within their disease.17 One had destruction of a large part of the right cranial vault; the other had most of his second cervical vertebra destroyed by metastatic squamous cell carcinoma. Isotretinoin controlled the  granulomatous acneiform lesions but had no effect on the cancers. but tends to heal centrally. The condition is extremely persistent and slow healing is a marked feature.  Disfiguring, sometimes keloidal, scars may accompany the progressive  extension of the lesions and many cases remain active for twenty years or more.

  Acne conglobata may be associated with obstruction and inflammation of the apocrine glands of the axilla, breast and perineum, producing the condition of hidradenitis suppurativa. It must be noted that hidradenitis  is  more frequently associated  with mild acne.

  Acne conglobata  and hidradenitis suppurativa  may have a familial tendency and so the distribution of HLA antigens in  such patients  and their relatives has been investigated.