A patient's skin and subcutaneous tissue can be infected anywhere in his hand. Pulp infections and paronychia are merely subcutaneous infections at the tip of a finger. If there is pus under the keratinized layers of his epidermis, strip these off, and see if you can find the hole through which it has tracked from a deeper abscess underneath. An abscess near the surface may communicate with pus deep inside his hand through a narrow opening. Pus like this forms a ''collar-stud abscess' as shown in Fig. 8-1. So, whenever you find a superficial abscess, look for the passage which might be joining it to a deeper one.
Carbuncles (5.4) may form in the hair follicles on the back of the fingers and hand. Antibiotics will not cure them, so deslough them.
DON'T BE MISLED BY A COLLAR-STUD ABSCESS Fig. 8-2 INFECTION AROUND THE NAIL. A patient can have pus on one side of his nail, either superficial (E), or deep (G). It may track all round his nail (A, and B) so that the proximal part of his nail needs excising (I to L). Avoid incising the ball of his finger (M) unless pus is already pointing there. N, and O, if infection is already present in several of the compartments of his pulp, you will have to make a lateral incision. Keep your incision away from his palmar skin, and not more than 3 mm from the edge of his nail. Note: In N, don't cut the end of his finger off; this is a schematic cross-section only! A, and B, after Flatt AB, ''Functional Anatomy', Fig. 14.2 with kind permission.