Primary Cutaneous Follicle Center Lymphoma Mimicking Folliculitis

Comment

Because the incidence of cutaneous B-cell lymphomas has been increasing, especially among males, non-Hispanic whites, and adults older than 50 years,¹ it is important for clinicians to have a high index of suspicion for this entity. In our patient, the clinical findings of a papular, largely asymptomatic eruption on the back with acute onset were initially thought to be consistent with folliculitis; the differential diagnosis included transient acantholytic dermatosis and miliaria rubra. Lymphoma was not in the initial clinical differential, and we only arrived at this diagnosis based on histopathologic evaluation.

The neoplastic cells typically are positive for CD20, CD79a, and BCL-6, and negative for BCL-2.⁴ Most cases of PCFCL do not express the t(14;18) translocation involving the BCL-2 locus, in contrast to systemic follicular lymphoma.¹ Systemic imaging and evaluation is needed to definitively differentiate PCFCL from systemic lymphoma with cutaneous involvement. Our patient was unusual in that BCL-2 was strongly staining in the setting of a negative systemic workup.

With regard to treatment of PCFCL, electron beam radiation therapy is highly effective and safe in patients with solitary lesions, as the remission rate is close to 100%.¹ For patients with multiple lesions confined to one area, electron beam radiation therapy also can be helpful, as in our patient. In patients with more extensive skin involvement, rituximab therapy may be preferable. Relapse following treatment with either radiation or rituximab occurs in approximately one-third of patients, but these relapses generally are limited to the skin.¹ The International Extranodal Lymphoma Study Group has noted that elevated lactate dehydrogenase, presence of more than 2 skin lesions, and presence of nodular lesions are negative prognostic factors in patients with PCFCL⁶; however, PCFCL has an excellent prognosis overall with a 5-year survival rate of 95%.¹

Other rare heterogeneous presentations of PCFCL have been reported in the literature. A large multinodular mass on the scalp with multifocal facial lesions has been described in a patient with essential thrombocytopenia.⁷ Another report identified a variant of PCFCL characterized by multiple erythematous firm papules that were distributed in a miliary pattern, predominantly on the forehead and cheeks.⁸ Barzilai et al⁹ described 4 patients with PCFCL who developed lesions that were clinically similar to rosacea or rhinophyma, including papulonodular eruptions on the cheeks; infiltrated erythematous nasal plaques; and small flesh-colored to erythematous papules on the cheeks, nose, helices, and upper back. Hodak et al¹⁰ identified 2 cases of PCFCL that manifested as anetoderma, a condition characterized by the focal loss of elastic tissue. In the setting of chronic lymphocytic leukemia, PCFCL has been observed as a red or violaceous nodule with a centrally depressed scar on the legs.¹¹ In one case, PCFCL manifested as recurrent episodes of extraorbital swelling and a multifocal red-blue macular lesion that extended from the inferior orbital rim to the nasojugal fold.¹² An interesting presentation of PCFCL was noted as a small, recurring, blood-filled blister on the cheek with perineural spread of the tumor along cranial nerves V2, V3, VII, and VIII.¹³ In the pediatric literature, PCFCL has been reported to present as an erythematous nodule with a smooth surface and a hard elastic consistency that appeared on the nose and nasolabial fold and spread to the ipsilateral cheek, maxillary sinus, and soft palate.¹⁴ In many of these unusual cases, the diagnosis of PCFCL was made after treatment with topical or systemic anti-inflammatory therapies failed.

Increased recognition of anomalous presentations of PCFCL among dermatologists can lead to more timely diagnoses and treatment. Based on our experience with this patient, we recommend considering biopsy for histopathologic evaluation when treating patients with presumed folliculitis or transient acantholytic dermatosis that does not improve with routine treatment or is accompanied by systemic symptoms.