PRODUCTS, ADVENTITIOUS. 



129 



modified by the presence of cell-pigment 

 within them. (7.) " Mela no tic tumours" are 

 rarely solitary, it is urged by Cruveilhier; 

 but this simply depends on the fact of ence- 

 phaloid cancer being the growth most fre- 

 quently impregnated with black pigment. 



The stromata above referred to are the only 

 kinds which we have ourselves seen or known 

 of as elements of black coloured tumours in 

 the luunan subject. But in the horse a species 

 of melanic mass of different constitution is 

 frequently met with ; and may, for aught we 

 know to the contrary, occur (if so, probably 

 only in rare instances,) in the human subject. 



These masses are of lobulated form, per- 

 fectly and deeply black in colour, sometimes 

 attain great bulk, and feel remarkably elastic 

 and spongy. Of the numerous specimens of 

 the kind in University College Museum, an 

 attempt has been made to inject one with a 

 white material ; a few spots of white colour in 

 the substance of the tumour alone give evi- 

 dence of the attempt ; no trace of vascular 

 arrangement is perceptible. A portion of the 

 mass having been allowed to macerate in 

 chlorine water for four days, the colour was 

 rendered sufficiently faint for observation of 

 the stroma. It consisted of delicate fibrils 

 (gelatinizing with acetic acid) arranged parallel 

 to each other, without the least appearance 

 of meshes. The pigment-granules, which 

 were not contained within cells, (at least, no 

 cells were visible), lay upon tl\e surface of 

 the fibres in some' places, so as on first sight 

 to give an appearance of cross lines ; in others 

 they lay between the fibres. The conviction 

 arises that this tumour may have been a 

 haematoma; absolute proof is, we admit, yet 

 wanting: if we are right, it would follow that 

 the only doubtful kind of black tumour we 

 have seen, possesses in reality, like all others, 

 a stroma of ascertained nature, with black 

 pigment added. And the observation lends 

 indirect support to the view (still unesta- 

 blished) of those who presume black pigment 

 to be, under all circumstances, formed from 

 the colouring matter of the blood. 



OF FAT-BASIS. 



Growths of fat-basis agree in not being 

 properly encysted, though they may occasion- 

 ally acquire a secondary capsule from con- 

 densation of adjacent cellular membrane. The 

 chief species are Lipoma, Steatoma, and 

 Cholesteatoma. 



1. LIPOMA. 



Lipoma is a growth of softish consistence, 

 somewhat elastic in form, generally disposed 

 to be globular, though occasionally distinctly 

 flattened ; frequently lobulated, and furrowed 

 on the surface ; varying in size from very 

 minute to vast dimensions, weighing from a 

 few grains to ten, twenty, or (if records be 

 true) forty pounds; ordinarily single, espe- 

 cially when of notable bulk : two or three of 

 the size of the clenched hand may, however, 

 not unoften be seen together ; and occasion- 



VOL. IV. 



ally, when of very small size, considerable 

 numbers coexist in the same individual. 



Lipoma most commonly forms in the sub- 

 cutaneous adipose texture (where it partakes 

 of the characters of hypertrophy), but appears 

 to be producible wherever cellular tissue 

 exists. Miiller has seen a lipoma between the 

 corpora albicantia and optic nerve ; Albers 

 (Pathologic, b. ii. s. 189), found a lipoma of 

 the size of a mushroom between the arachnoid 

 and dura mater, on the level of the fourth 

 lumbar vertebra ; Andral (Anat. Path. ii. 412) 

 describes one as large as a walnut, seated in 

 the walls of the vena portae. Growing between 

 the peritoneum and abdominal wall, lipoma 

 sometimes escapes by the abdominal rings, 

 and constitutes the so-called " fatty hernia." 

 In a fatal case of infiltrated cancer of the 

 right lung, which lately occurred in our wards 

 (Univ.-Coll. Hosp.) a lipomatous mass had 

 formed in the pleura of the affected side. 



Lipoma on section, and even externally, 

 presents the appearance and possesses the 

 physico-chemical properties of common adi- 

 pose tissue. The fatty elements, (margarin 

 and olein) are removable with boiling aether. 

 Microscopically the fat is found to be con- 

 tained in cells, of the natural size, aggregated 

 in parcels amid and upon the fibres of a deli- 

 cate cellular tissue ; the dimensions of the 

 mass have no influence on its intimate con- 

 stitution. The cells commonly of rounded 

 shape, become much more rarely polyedral 

 from lateral pressure, and are for the most 

 part non-nucleated. 



Their contained fat is fluid at the tempera- 

 ture of the body : when cool, separation of the 

 olein and margarin takes place (as shown by 

 Messrs. Todd and Bowman in the case of 

 natural fat) and star-like groups of crystals of 

 the latter form in the interior of the cell. We 

 have occasionally seen free oil globules in 

 lipoma, but whether arising from accidental 

 rupture of containing cells or not, we cannot 

 determine. The vessels of lipoma are of small 

 size, and ramify in its stroma. 



A delicate laminar cellular membrane in- 

 vests the majority of lipomata ; infiltration 

 of texture is never effected by these growths. 

 Their cellular investment may become fibrous, 

 giving them a pseudo-encysted character. 

 Pedunculation (single or multiple) is not un- 

 common ; the peduncle sometimes stretching 

 away to some distance from the main part of 

 the growth ; from the front of the sternum, 

 for instance, deeply into the mediastinum. 



The natural course of lipomata is to increase 

 almost indefinitely in bulk, without giving rise 

 to any other inconvenience than that arising 

 from their size, weight, and position. The 

 surrounding skin bears without ill results an 

 extraordinary amount of distension ; though 

 eventually attenuation, low inflammation and 

 gangrene have sometimes ensued. Lipomata 

 are susceptible of inflammatory softening, 

 (a rare occurrence however) leading to break- 

 ing down of their substance ; the physical, 

 and probably chemical qualities, of the fat 

 change materially. Growths thus altered have 



