Papules, Nodules, and Ulcers

Papules, nodules, and ulcers are primary lesions of the skin with a variety of infectious and noninfectious causes ( Tables 72.1 and 72.2 ). A papule is a raised superficial lesion that is less than 1 cm in diameter whose surface may be smooth, scaly, or hyperkeratotic. A larger (>1 cm), raised, and often flatter-topped lesion is called a plaque. A nodule is a solid, palpable lesion that is larger than 1 cm in diameter. An ulcer is a loss of skin to the level of the dermis or deeper. An erosion is shallower, and the loss of skin is limited to the epidermis.

Particular cutaneous lesions can be associated with a specific organism (e.g., umbilicated papule with molluscum contagiosum [MC], hyperkeratotic papule with human papillomavirus [HPV]), or multiple morphologic lesions can occur through the course of infection due to a single organism. For example, in tuberculosis or sporotrichosis, an initial papule can enlarge to form a nodule and then break down to an ulcer. The papular or nodular lesions can consist of a proportionately large volume of the infectious agent (e.g., poxvirus of MC), almost exclusively of inflammatory cells (e.g., histiocytes within well-controlled primary cutaneous tuberculosis), or frequently a combination of the inciting agent and inflammatory reaction.

Nodular lymphangitis , often referred to as sporotrichoid lymphocutaneous infection or sporotrichoid spread in dermatology, is a distinctive, underrecognized pattern resulting from cutaneous inoculation of a relatively limited number of agents (e.g., Sporothrix schenckii, Francisella tularensis, Alternaria, Nocardia brasiliensis, Nocardia asteroides, Mycobacterium marinum, other Mycobacterium species , Fonsecaea pedrosoi, Leishmania, Yersinia , Francisella, and Staphylococcus aureus ) and is characterized by a linear pattern of lymphadenopathy often proximal to the site of the primary inoculation. Chronic nodular lymphangitis due to any cause can become ulcerative. ^,

A variety of nonspecific reactive lesions can manifest in the skin as a result of an infectious process elsewhere (e.g., erythema nodosum as a sign of streptococcal pharyngitis). The eruptions result from a disordered immune response after infection. At the time of lesion development, organisms usually are not recoverable ( Box 72.1 and Table 72.3 ). Drug reactions in children also can manifest as papules or rarely as nodules, often in the setting of a concurrent viral infection, which can be confused with a response to the infection.