A CASE illustrating this rare condition came under my care in June last, and presented the following features: A single woman, aged 22, attended my out-patients' department at St. Thomas's, and complained that during the previous two years a lump had been growing in her armpit; its progress had been slow and not attended by any discomfort until the last fortnight, when it had become painful. Examination disclosed at the dome of the right axilla and rather to its outer wall a convex lump about

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... e size of a pigeon's egg with its long axis corresponding to that of the arm. The skin was unaitered but stretched over it, and free all over except at one point, which agreed with a slight depression, the apparent opening of a duct of one of the axillary sudoriparous glands. The lump was in the substance of the stin, and they together could be lifted up from the subjacent fascia; there was evident elasticity-denoting fluid, which latter was confirmed by the marked translucency of the tumour. Having had a previous case, as noted below, I made a correct diagnosis and proved the same by its removal. Section showed it to be a skin cyst consisting of one large cavity containing a thin watery fluid; the lining was in general smooth, but over an area the size of a sixpence soft papillary growths were attached. 4 Histologically the connective tissue of the cyst wall is seen to bn sharply defined from its epithelial lining. The latter over the mai part of the cyst consists of two or three layers of cubical cells flattened by pressure. The papillary processes show a many-layered epithelium, the surface cells being swollen and vacuolated, as is frequently seen in secreting glands. The appearances suggest an origin from that portion of the duct between the epidermis and the coiled tube. The tubes of the coil in places are dilated, but without any papillary growths. This class of cyst appears to be very rare, for any literature bearing on the subject is extremely scanty. Curiously my other case' was almost identical. This was from a little girl aged 13, and the tumour was the size of a Barcelona nut, and situated in the outer wall of the axilla. On examination it proved to be multilocular, with one cyst much larger than the others; from several spots on the wall of the largest cyst were sprouting papillary growths which histologically showed a fibrous core upon which were placed layers of a stratified epithelium with the surface cells vacuolated. The contained fluid was thin and clear like water. Dr. H. D. Rolleston2 records a very similar case where the tumour was situated over the left parotid region. Unna, in his work on the Histo-pathology of the Skin, says that cysts of the sudoriparous glands are only known of the duct and not of the coil. Small cysts, generally related with scars, may ariso within the epithelial layer, and he terms these "poro-cysts." Cysts from the other part of the duct are placed in the corium, and contain sweat " hydracystoma ": there is no reference to these latter having papillary growths. It is very evident that in this condition we have to deal with retention cysts of the gland, and there is no more likely place in the body for such to occur than the axilla, where the glauds are so well developed and the possibilities of blocking of the duct with dirt so great. Dr. Rolleston compares the appearances with those seen in a duct-papilloma of the breast. In both cases, no doubt, irritating material enters via the duct, and sets up such surface change as to cause the formation of the papillary growths: retention of the secretion, when it occurs, is brought about-by the papillary growths and maintained by the cyst tension, causing distortion of the duct.