Patients with PFM are more frequently younger (mean age 39 years) and the female:male ratio is 3:1. In contrast, patients with LAFM are more often older (mean age 54 years) with a male:female ratio of 2:1.³

The clinical lesions of PFM are frequently solitary. They display various morphologies from hypopigmented macules and patches to erythematous, sometimes scaly papules and plaques, sometimes with follicular prominence.⁴ PFM lesions tend to concentrate around the head and neck and might present as acneiform eruptions⁵ (Fig. 42-1). Other locations, such as trunk and extremities, are not uncommon (Fig. 42-2). Nonscarring alopecia and pruritus can be present. The lesions are often persistent but tend to follow a benign albeit chronic course.⁴ Rarely, these cases evolve into MF^6,7 or precede the development of Hodgkin disease.^8,9,10,11

LAFM is generally distributed more diffusely as patches and plaques along with areas of alopecia.⁵ Most commonly, this is seen in the context of cutaneous T-cell lymphoma (CTCL) such as folliculotropic MF (FMF) or Sézary syndrome.^3,12 To some authors, FM may be a variant of FMF.¹³ A recent systematic review of FMF suggests that FM can be found in 74% of biopsy specimens reviewed.¹⁴ Interestingly, some cases of FMF can present with circulating atypical lymphocytes without erythroderma. If the histologic findings show clearly a pattern of MF and there are abnormal lymphocytes in the blood, these cases are best treated at FMF. However, because MF itself may be indolent, this association with lymphoma may develop over time.⁶