These tumors were first studied histologically by Balzer and Menetrier* in 1885, but they failed to recognize the true nature of the growths. Brooke* in 1892 and Fordyce* in the same year independently investigated the lesions and arrived at a proper solution of the problem.

Clinical Course

Clinically, the disease is more apt to occur in women (Fig. 40), usually those past middle life, and there is a marked tendency for the disease to run in families, several members frequently being involved. The site of predilection is the face. The tumors are translucent and vary in size from 2 to 8 mm. in diameter. They vary in number from six to twenty. Usually the growths remain stationary for many years, a few new ones occasionally appearing, but the older ones showing no tendency to either enlargement or to spontaneous disappearance. In a few cases malignant change has taken place, this having occurred in the cases reported by J. C. White,* Jarisch,* Stelwagon,* Sutton and Dennie,* and Strobel.9 Heidingsfeld* is inclined to believe that all tumors of this class are premalignant in both structure and character, but Sutton strongly dissents from this view.

*Sutton: Jour. Amer. Med. Assn., 1912, lviii, 333.

*Jour. Cutan. Dis., 1911, xxix, 480. Amer. Jour. Med. Sc., 1913, cxlv, 819.

*Balzer and Menetrier: Arch. f. Physiol., 1885, 565.

*Brooke: Brit. Jour. Denrat., 1892, iv, 269.

*Fordyce: Jour. Cutan. Dis., 1892, x, 459.

*White: Jour. Cutan. Dis., 1894, xii, 477.

*Jarisch: Arch. f. Dermat. u. Syphii., 1892, 269.

*Stelwagon: Diseases of the Skin, Phila., 1910.

*Sutton and Dennie: Jour. Amer. Med. Assn., 1912, lviii, 333. • Strobel: Personal communication.

*Heidingsfeld: Jour. Amer. Med. Assn., 1912, lvix, 256.

Pathology

Histologically, there are two distinct types-the Brooke type, where the tumor is derived from the basal layers of the rete, and the Jarisch type, where the proliferation is from the hair follicles. In both types the picture is somewhat similar, for "extending down into the corium from the basal layer were numerous fine, long, slender chains of epithelium, two or three cells in width, which terminated in bulb-like cysts, filled with colloid material and corneous material." These collections of horny matter are undoubtedly snared off from the horny layer, as so well illustrated by Krompecher in examples of the basal-celled tumors. In some cases there is an additional subdividing of the downgrowths. In addition to these changes, cysts are found in the upper portion of the prickle layer, filled with hornificd material. There may be a considerable amount of small round infiltration in the corium (Fig. 41).

Fig. 40.-Multiple benign cystic epithelioma. (C. J. White's collection).

Nomenclature

Inasmuch as the cells are distinctly basal in character, the author feels that the name proposed by Unna* and adopted by Sutton-namely, Acanthoma adenoides cysticum-is an unfortunate one, for the term acanthoma should refer entirely to tumors derived from the prickle layer. The name Basocelluloma adenoids cysticum would be nearer the correct term, and only the disinclination to further incumber the dermatological nomenclature prevents the author from adopting it.

*Unna: Histopathology of Diseases of the Skin.