PAPULONECROTIC TUBERCULID - A CLINICAL, HISTOPATHOLOGICAL, AND IMMUNOHISTOCHEMICAL STUDY OF 15 PATIENTS

We report 10 women and five men with papulonecrotic tuberculid, an unc ommon form of cutaneous tuberculosis (TB). The mean age was 22.6 years (range, 21/2-35 years) at presentation. The Mantoux test was strongly positive in 13 patients. Five patients showed presumptive evidence of associated TB; in one case, the presence of TB was proven by culture. Response to anti-TB was dramatic in all cases. Clinical findings were similar to those previously published. We emphasize the simultaneous occurrence of erythema induratum, associated Takayasu's disease, possi ble associated phlebitic tuberculid, and clinical mimicry of acute bac terial endocarditis. The main histopathological findings obtained from 27 biopsy specimens included dermal necrosis (26 of 27 cases), a poor ly formed granulomatous infiltrate (27 of 27 cases), vasculitis (11 of 27 cases), perivascular spongy edema (11 of 27 cases), and follicular necrosis or suppuration (five of 27 cases). A Ziehl-Neelsen stain was negative in all biopsy specimens. Immunohistochemical labeling reveal ed a preponderance of T-lymphocytes (UCHL-1+), monocytes-macrophages ( S-100+), and Langerhans cells (ACT+), indicative of a type IV hypersen sitivity reaction. B-lymphocytes (L26+) were sparse. Conditions that m ay be confused with PNT on clinical or histopathological ground includ e pityriasis lichenoides et varioliformis acuta, papular urticaria, pa pulopustular syphilide, miliary TB, septicemia, perforating granuloma annulare, chondrodermatitis nodularis, reactive perforating collagenos is, allergic granulomatosis, suppurative folliculitis, and infectious causes of palisading granulomas. Papulonecrotic tuberculid has distinc t clinical, histopathological, and immunohistochemical features. Aware ness of this entity is important since an appropriate diagnosis is nec essary for the institution of timely curative treatment.