Plasma Cell-Predominant Lichen Planopilaris.

ABSTRACT: Lichen planopilaris (LPP) is a scarring alopecia that is characterized by a lichenoid interface infiltrate with follicular extension. We present a case of LPP composed predominantly of plasma cells in a 52-year-old man. The patient was originally diagnosed with scalp psoriasis 30 years before presentation. Punch biopsies performed at an outside institution 2 years before presentation revealed lymphocyte-predominant LPP. After referral to the senior author's institution due to inadequate response to therapy, biopsies demonstrated a robust, superficial, and deep lichenoid interface dermatitis composed predominantly of plasma cells. Immunohistochemical and special staining for CD138, MUM-1, kappa and lambda light chains, immunoglobulin G4, CD3, CD20, PAX5, CD5, CD7, CD4, CD8, CD43, CD123, Gram, Grocott's methenamine silver stain, treponemal antibody, colloidal iron, and Movat showed a scarring alopecia and were not supportive of a hematolymphoid, infectious, or autoimmune etiology. B-cell clonality studies were below the threshold needed for definitive diagnosis of a clonal process. Doxycycline and hydroxychloroquine were subsequently added to the patient's treatment regimen, leading to an improvement of symptoms. We present this case to bring awareness to this unusual feature and discuss its differential diagnosis.

Cutaneous symplastic hemangioma: A series of four cases.

Symplastic hemangiomas (SH) are benign vascular lesions that show atypia in vascular smooth muscle and interstitial cells with sparing of endothelial cells. We present four cases of this rare tumor. The patients (two males; two females) ranged in age from 57 to 83 years (median 74); lesions were located on the leg (n = 3) and back (n = 1), and ranged from 6 to 8 mm. SH were well-circumscribed and dermal-based, often with an epidermal collarette (3/4). They were characterized by the presence of variably atypical, hyperchromatic/pleomorphic epithelioid to spindled cells within vascular walls (3/4) and/or perivascular stroma (4/4). Atypical multinucleated cells were present in three of four cases. The overall mitotic rate was low (0-2 mitotic figures per 10 HPFs; mean 0.75 per 10 HPFs), but atypical mitotic figures were seen in two of four cases. Atypical cells were negative for SMA (0/2), desmin (0/2), AE1/3 (0/2), and CAM5.2 (0/1). ERG, CD31, and CD34 stains were positive in endothelial cells but negative in atypical cells (4/4). Lesional cells and vessels were negative for podoplanin (3/3). Symplastic hemangioma is a benign tumor with bizarre atypia that may be mistaken for malignancy. We present four cases of this rare entity to increase awareness of this tumor and discuss the differential diagnosis.