There are various dermatologic presentations that should raise the suspicion for an underlying malignancy and may lead to a diagnosis in a small percentage of patients.
The prevalence of underlying malignancy depends on the specific eruption, but a workup is required in all cases for the most common causes.
The most common underlying malignancies vary for each paraneoplastic dermatosis, and therefore screening recommendations are distinct for each eruption.
The malignancy may not be present at the time of onset of rash and can present months to years after.
PATIENT EDUCATION POINTS
There are various dermatoses that have been reported to be associated with an internal malignancy. In patients with such a dermatosis, it is important to devise and perform an appropriate evaluation for a malignancy. Paraneoplastic skin diseases can provide the first clue to a diagnosis of malignancy in 1% of cancers.1 To meet the criteria of a paraneoplastic disease, the condition must fulfill the Curth postulates, which include a concurrent onset between the dermatosis and malignancy, both conditions following a parallel course, uniformity of a particular malignancy in association with a specific dermatosis, a statistically significant association between the two, and/or a known genetic basis between the malignancy and dermatosis. Although not all criteria must be met, several should be fulfilled to qualify as a paraneoplastic disease. In this chapter, we will review various cutaneous conditions that are associated with malignancy and fulfill many of these postulates, including those that have a high association with malignancy and those seen with malignancy only in a subset of patients.
DISORDERS ASSOCIATED WITH CANCER IN MOST OR ALL CASES
Hypertrichosis Lanuginosa Acquisita
Hypertrichosis describes excess growth of hair and can involve lanugo, vellus, or terminal hairs. Hypertrichosis lanuginosa occurs when there is excess growth of lanugo hairs, which are thin, unpigmented, and woolly in texture.2 There are two main forms of hypertrichosis lanuginosa: a congenital form (hypertrichosis lanuginosa congenita or HLC) and an acquired form (hypertrichosis lanuginosa acquisita or HLA). Although HLC can be seen as a normal phenomenon in premature neonates or as a hereditary condition, HLA is seen in association with underlying malignancy or systemic disease and must be investigated.
HLA is seen predominantly in women and typically occurs between the ages of 40 and 70 years.2 HLA may occur in patients with underlying metabolic and endocrine diseases, including thyroid disorders, AIDS, and anorexia; in response to drug therapy, such ...