An unusual case of cutaneous Waldenström macroglobulinemia with the MYD88 L265P mutation

Waldenström macroglobulinemia is a lymphoplasmacytic lymphoma with bone marrow involvement and a monoclonal IgM gammopathy. Infiltration of the skin by neoplastic cells is very rare, and it can be difficult to distinguish from marginal zone lymphoma. The MYD88 L265P mutation is strongly associated with Waldenström macroglobulinemia, and it may be helpful in differentiating the two disorders, although the presence of this mutation is not specific, and other factors must be considered when making the final diagnosis. We present a diagnostically challenging case of cutaneous Waldenström macroglobulinemia in which the MYD88 L265P mutation was identified in the skin but not in the bone marrow, due to a low tumor burden.     

A rare case of invasive melanoma likely arising from passenger melanocytes of a basal cell carcinoma

Neoplasms consisting of different cell lineages within a single skin specimen are rare, yet well documented in the literature. However, to date, there appears to be no report of invasive melanoma arising directly from the passenger melanocytes of a basal cell carcinoma (BCC). We present a case of a 91-year-old male with a suspicious lesion on the ear. Histopathology and immunohistochemical staining revealed BCC closely intertwined with invasive melanoma that exhibited foci of chondroid differentiation. The melanoma appeared to arise from the benign-appearing passenger melanocytes of the BCC and lacked connection to the overlying epidermis or an in situ component. Multiple dermatopathologists reviewed the case and agreed that the most likely explanation for the histopathologic findings was that the invasive melanoma arose from the passenger melanocytes within the BCC.     

Spindle cell melanoma coexisting with chronic lymphocytic leukemia/small lymphocytic lymphoma: a rare collision tumor in multiple sites

A strong association has been reported between chronic lymphocytic leukemia/small lymphocytic lymphoma (CLL) and malignant melanoma (MM). In rare cases of MM, lymphoid malignancies may be detected incidentally during sentinel lymph node biopsies. In this case, we found a unique collision of MM and CLL infiltration in the skin. An 88-year-old male patient presented with a mass on the nasal root. Histopathological examination of the skin biopsy specimen revealed a deeply infiltrative, atypical spindle cell proliferation in the background of a collagenous stroma. Accompanying this lesion, there were foci of monotonous lymphoid cell populations involving skin appendages. In the immunohistochemical studies, the spindle cells were diffusely positive for S100, and focally positive for Melan-A and HMB45; the lymphoid cells were positive for CD20, CD5, and Bcl-2 and negative for CD3, Bcl-6, CD10, and Cyclin D1. Histopathological and immunohistochemical findings were consistent with diagnoses of spindle cell melanoma and CLL. Interestingly, these two tumors together in their same morphological appearance were confirmed in a subsequent liver biopsy. Active skin surveillance of patients with CLL may be important to detect MM at an early stage that correlates with a better prognosis.     

Acantholytic pityriasis rubra pilaris associated with topical use of imiquimod 5%: case report and literature review

Topical use of immune response modifiers, such as imiquimod, has increased in dermatology. Although its topical use is well tolerated, it may be associated with exacerbations of generalized cutaneous inflammatory diseases, possibly through the systemic circulation of pro-inflammatory cytokines. This report describes a case of development of pityriasis rubra pilaris, a rare erythematous-papulosquamous dermatosis, in a woman aged 60 years during treatment with imiquimod 5% cream for actinic keratosis. It evolved with erythrodermic conditions and palmoplantar keratoderma, presenting progressive clinical resolution after the introduction of methotrexate. The authors emphasize the importance of recognizing possible systemic reactions associated with the topical use of imiquimod.     

Eruptive disseminated Spitz nevi – Case report

Spitz nevus is a benign melanocytic lesion, which presents in several ways: solitary, agminated, or disseminated. The disseminated variant is uncommon; it may have a rapid evolution (the eruptive form) and be difficult to manage. This report presents the case of a 24-year-old patient with multiple papules on his limbs, which had appeared four years previously. On physical examination, 120 pink and skin-colored papules were seen, which under dermoscopy were observed to be homogeneous, pink vascular lesions. Histopathologic study revealed epithelioid cells arranged in groups or singly in the dermis and dermo-epidermal junction. They were HMB-45 positive in the superficial dermis, and Ki-67 < 1%. Given these findings, a diagnosis of eruptive disseminated Spitz nevi was made.     

Safety of local anesthetics

Local anesthetics are essential medications for the conduction of dermatological procedures. They stop the depolarization of nerve fibers and are divided into two main categories, the amide and ester types. Systemic toxicity with reflex on the central nervous and cardiovascular systems is their most feared adverse reactions, and the anaphylactic reaction is the most concerning one. Although potentially fatal, these events are extremely rare, so local anesthetics are considered safe for use in in-office procedures.     

Update on parasitic dermatoses

These are cutaneous diseases caused by insects, worms, protozoa, or coelenterates which may or may not have a parasitic life. In this review the main ethological agents, clinical aspects, laboratory exams, and treatments of these dermatological diseases will be studied.