The integuments nearly always participate in the changes, and are necessarily augmented in extent where covering the enlarged bones. The derm does not appear to be much altered in structure, but Eve found in the skin over the hypertrophied sole a thinning of the rete with almost complete obliteration of papillæ and enormous thickening of the fibrous tissues and inter-fascicular lymph spaces; but these changes were probably due to the abnormal pressure and friction to which the part was exposed. The subcutaneous adipose layer commonly shows a diffuse thickening, and in addition may undergo a circumscribed hypertrophy in the form of large lipomatous pads, which are mostly found upon the flexor aspect of the member affected, and correspond in situation and extent to the bony enlargement ([Fig. 18]); but the papillary and epithelial layers do not undergo any sensible changes, nor, as a rule, are the hairs or sebaceous follicles more developed than on the opposite side. The nails of hypertrophied digits generally undergo proportionate development. The secretion of perspiration is seldom altered in amount or character, but in a case of Wittelshöfer the patient complained of profuse sweating from the affected limb. The cutaneous sensibility is variously described as unaffected or diminished, never increased. A reduction of the sensibility to heat and pain was found to accompany the tactile defect in von Fischer’s case, and it is probable, as he suggests, that careful examination would generally reveal an impairment of the faculties. Pain is rarely complained of. Burning pain was present in association with trophic ulceration in a case of von Fischer, and pains of a rheumatic character appeared in the author’s case, but this symptom probably formed no part of the original disease.
The temperature of the part is generally normal. By exception, a rise of 2°-2½° Fahr., of 2°-6° Fahr. (Reid), 2°-4° Fahr. (Finlayson), and of ½°-1° Cent. (Trelat and Monod) has been recorded.
Pathological complications are rarely met with. Trophic ulceration appeared in a case of von Fischer’s; and in Friedberg’s case an eruption resembling pemphigus was noted, but probably was not directly connected with the congenital hypertrophy. Inflammatory crises, corresponding to those of elephantiasis Arabum, have been seen in only one instance, and in this the condition appeared to be complicated by true elephantiasis.
Associated defects of development are frequent in connection with makrodactyly. They may consist of multiplication, dwarfing, absence, or fusion of parts. The most common defect is syndactyly. Secondary distortions of the spine are found, however, when the hypertrophy of a single limb is very great. The general health does not appear to be affected by the condition.
Pathology.—The older views as to the pathological origin of congenital hypertrophy leave us little advanced towards a solution. The condition has been attributed to a congenital lesion of the vaso-motor centres; to a primitive vice in the mesoblast; and to an inherent tendency of the affected tissues to appropriate an excess of nutriment; but these theories only lead to the same point—that for some reason which our pathology is still inadequate to explain, there is a weakening of the governing power that regulates the ratio between supply and demand in the tissues; or, to quote from Professor Humphry (l.c.), “The cases obviously consist in an excess, an abnormally excessive growth of a normal part of the body—an excess not depending upon any superabundance of nutritive supply, or any modification of nerve influence, but upon an excess, a want of due restraint, of that developmental force by which the several organs and structures acquire and maintain their proper dimensions and relations to one another, and by which their relative growth at different periods of life and under different circumstances (as of the genital organs at puberty). The nature and essence and habitat or source of the force is a mystery, perhaps past finding out.”
This sums up the whole question. It is probably the same kind of misgovernment of tissue that leads to certain other deformities occurring both before and after birth, and to the development of some forms of new growth. How it originates remains for the pathologists of the future to decide.
Treatment.—No means yet devised has any power of restraining the tendency for the excessive and irregular growth in this condition. The only resources of the surgeon are to correct associated deformities as far as possible, and to remove parts that are sufficiently inconvenient or disfiguring to warrant the use of the knife.
SUPERNUMERARY FINGERS AND TOES.
The occasional occurrence of supernumerary fingers and toes is well known. As a rule the extra digit is a mere pediculated appendage bearing a nail and a more or less perfect representative of the ungual phalanx; in other cases, however, it is complete and well formed, and furnished with a metacarpal or metatarsal bone of its own, or sharing the proximal bone with a neighbouring finger or toe. In rare instances the digits may undergo still further numeral increase even to a complete duplication of the normal complement.
The condition is commonly bilateral, and may affect all four extremities. It is liable to association with syndactyly and other congenital deformities, and it is occasionally handed down by inheritance as a family peculiarity. Sir William Lawrence refers to a condition of the kind which was traced through four generations, and other examples are on record.