Deon Wolpowitz

Nests with numerous SOX10 and MiTF-positive cells in lichenoid inflammation: pseudomelanocytic nests or authentic melanocytic proliferation?

Pseudomelanocytic nests in the setting of lichenoid inflammation can mimic atypical melanocytic proliferations. Both melanocytic and cytokeratin immunohistochemical stains may be utilized to differentiate these entities. Unlike true melanocytic nests, pseudomelanocytic nests contain Melanoma Antigen Recognized by T‐cells 1 (MART‐1)/ Melan‐A‐positive cells and cells positive for pan‐cytokeratins, CD3 and/or CD68. Recently, rare (1–2 cells/nest) microphthalmia‐ associated transcription factor (MiTF)‐positive cells were also reported in pseudomelanocytic nests. We present a 48‐year‐old man with a 2 × 3 cm violaceous to hyperpigmented, non‐blanching, polygonal patch on the neck. Histopathology showed focal epidermal atrophy, irregularly distributed junctional nests and a lichenoid infiltrate with colloid bodies. Immunoperoxidase studies revealed occasional pan‐cytokeratin and MART‐1/Melan‐A‐positive staining in nests as well as focal S‐100 protein‐positive cells. Importantly, the majority of nests showed numerous cells positive for MiTF and SOX10 (>2 cells/nest and some the majority of cells). This combined staining pattern confounds the above‐described immunohistochemical distinction between pseudo and true melanocytic nests. Clinically felt to represent unilateral lichen planus pigmentosus/erythema dyschromicum perstans and not malignant melanoma in situ, this lesion highlights the importance of clinicopathologic correlation and suggests either a new melanocytic entity or a novel pattern of benign melanocytic reorganization in a subset of lichenoid dermatitides.

CCR4 T cell recruitment to the skin in mycosis fungoides: potential contributions by thymic stromal lymphopoietin and interleukin-16

Abstract Mycosis fungoides (MF) is characterized by skin accumulation of CCR4+CCR7- effector memory T cells; however the mechanism for their recruitment is not clearly identified. Thymic Stromal Lymphopoietin (TSLP) is a keratinocyte-derived cytokine that triggers Th2 immunity and is associated with T cell recruitment to the skin in atopic dermatitis. Interleukin-16 (IL-16) is a chemoattractant and growth factor for CD4+ T cells. We hypothesized that TSLP and IL-16 could contribute to recruitment of malignant T cells in MF. We found elevated TSLP and IL-16 in very early stage patients’ plasma and skin biopsies, prior to elevation in CCL22. Both TSLP and IL-16 induced migratory responses of CCR4+TSLPR+CD4+CCR7−CD31+ cells, characteristic of malignant T cells in the skin. Co-stimulation also resulted in significant proliferative responses. We conclude that TSLP and IL-16, expressed at early stages of disease, function to recruit malignant T cells to the skin and contribute to their enhanced proliferation.

Gastrin-releasing peptide-expressing nerves comprise subsets of human cutaneous Aδ and C fibers that may sense pruritus.

TO THE EDITOR Itch sensation is transmitted from the skin to the spinal cord by small-diameter, unmyelinated C fibers and thinly myelinated Aδ fibers (Schmelz, 2010; Ringkamp et al., 2011). In human skin, C fibers mediating pruritus are either mechanically insensitive, histamine-sensitive nerves or mechanically sensitive, polymodal nociceptors that are unresponsive or only weakly responsive to histamine (Schmelz, 2010; Ringkamp et al., 2011). In addition, data combined from human and nonhuman primate experiments identified mechanically sensitive Aδ fibers that contribute to histamine-induced and non-histamine, cowhage spicule–induced itch (Ringkamp et al., 2011). Histologic markers for itch-sensing nerves in human skin include the capsaicin receptor, transient receptor potential vanilloid 1 (TRPV1) (Schmelz, 2010; Ringkamp et al., 2011), and the vasoactive peptides calcitonin gene–related peptide (CGRP) or substance P (SP) (Davidson and Giesler, 2010). However, these histologic markers alone cannot differentiate Aδ and C fibers that perceive itch from those that sense pain. In rodent models, gastrin-releasing peptide receptor (GRPR), expressed in the dorsal horn lamina I, mediates a central nervous system itch–specific pathway (Sun and Chen, 2007; Sun et al., 2009). In mice, gastrin-releasing peptide (GRP), the ligand for GRPR, is expressed in both the skin and the dorsal root ganglion by peptidergic (i.e., containing CGRP and SP) nerves that express TRPV1 (Sun and Chen, 2007; Liu et al., 2009; Tominaga et al., 2009; Lagerstrom et al., 2010; Fleming et al., 2012). Although GRP is not likely to be the principal excitatory neurotransmitter activating GRPR-expressing spinal cord dorsal horn neurons, GRP-expressing neurons still may mediate itch-specific signals from the skin to the spinal cord in rodents (Lagerstrom et al., 2010; Akiyama et al., 2012). Accordingly, MrgprA3 expression defines a subset of mouse primary cutaneous sensory neurons that mediate itch, and 93% of MrgprA3-positive neurons coexpressed GRP (Liu et al., 2009; Han et al., 2012). Given the putative role of GRP-expressing nerves in mediating itch in these animal models, we sought to determine whether nondiseased human skin contains GRP-expressing nerves that show histologic features of primary afferent pruriceptors. Disease-free human skin from 17 patients (nine women, mean age 66.9 years±14.7; eight men, mean age 61.2 years±9; Supplementary Table S1 online) was used for fluorescence immunohistochemistry on 80-μm-thick sections (see Supplementary Methods online). GRP(+) nerves (confirmed by costaining with protein gene product 9.5 (PGP9.5)) were identified in all patients and from all sites (Table 1, Supplementary Table S1 online). GRP(+) nerves were primarily located in the papillary dermis as free nerve endings terminating at the dermoepidermal junction (DEJ) (Figure 1), and in this anatomic skin compartment comprised between ∼5 and 15% of all PGP9.5(+) staining (Supplementary Table S1 online). GRP(+) nerves were not identified within the epidermis of human skin but were identified tightly associated with some appendageal structures, including hair follicles and eccrine glands (Supplementary Figure S1 online). Determining regional variation in GRP nerve density has relevance to future studies comparing diseased with nondiseased skin. After categorizing the samples into three anatomic locations (scalp/head/neck, trunk, and extremities), we found only modest site differences in the % of PGP9.5 nerve length that is GRP(+) at the DEJ (Table 1), indicating near-uniform anatomic distribution of GRP(+) nerves in human papillary dermis. Figure 1 Characterization of gastrin-releasing peptide (GRP)-expressing nerves in the dermoepidermal junction (DEJ)/papillary dermis in human skin. Immunohistochemical triple staining showing (a, d, and g) GRP, (b) calcitonin gene–related peptide (CGRP), ... Table 1 Human papillary dermis nerve staining results Itch-sensing fibers are thought to be peptidergic, expressing SP and CGRP (Davidson and Giesler, 2010). We identified GRP expression in both CGRP(+) and CGRP(−) (Figure 1 and Supplementary Figure S1 online, Supplementary Table S2 online) and SP(+) and SP(−) nerves (Figure 1, Supplementary Table S3 online) at the DEJ. The majority of papillary dermal GRP(+) nerves were SP(+) (median 98.2, 25–75% quartiles, 32.8–100%), whereas these GRP(+) nerves were significantly less likely to be CGRP(+) (median 50.9, 25–75% quartiles, 18.8–80% P=0038). Similarly, GRP(+) neurons comprised a significantly larger proportion of SP(+) nerves at the DEJ (median 86.4, 25–75% quartiles, 40.0–100%) than of CGRP(+) nerves (median , 28.0, 25–75% quartiles, 8.1–43.3% P<0.0001). Finally, this GRP antibody colabeled with a peptidergic nerve fiber population in mouse skin (Supplementary Figure S2 online, Supplementary Table S4 online), similar to that previously reported (Sun and Chen, 2007; Liu et al., 2009; Tominaga et al., 2009; Lagerstrom et al., 2010; Fleming et al., 2012). As both Aδ and C fibers mediate itch, we next examined whether GRP(+) fibers at the DEJ belonged to the Aδ fiber (neurofilament 22 (NF200)+) and/or the C fiber (NF200−) populations of nerves (see Methods). Combining the 17 subjects, GRP(+) nerves comprised 38.1% (median, 25–75% quartiles, 8.7–60.0%) of C fibers and 66.3% (median, 25–75% quartiles, 41.0–91.3%) of Aδ fibers (Figure 1, Table 1), with this difference being significant (χ2 7.63, DF1, Prob>χ2 0.0057). The majority of GRP(+) C fibers and GRP(+) Aδ fibers coexpressed SP (median 88.4, 25–75% quartiles, 34.3–100% median 100, 25–75% quartiles, 95.9–100%, respectively) (Figure 1). Our identification, in human skin, of GRP-expressing C and Aδ fibers that coexpress either SP or CGRP makes these neurons candidate primary afferent pruriceptors. Moreover, putative broad GRPR expression in human skin, including keratinocytes, makes possible additional functions for this nerve population (Staniek et al., 1996). As for SP and CGRP nerves, GRP-expressing nerves comprised a minority of the nerve plexus in human papillary dermis and predominantly terminated at the DEJ without intraepidermal extension. Itch-specific signaling has been known to reside superficially in human skin (Magerl, 1996). However, whether human intraepidermal nerve fibers (IENFs) and/or papillary dermal nerves signal itch is not clear. Pain-sensing pathways, thought to reside deeper in the dermis, may block, at the level of the spinal cord, a coactivated superficial itch signal (Davidson and Giesler, 2010; Schmelz, 2010; Ross, 2011). This superficial itch signal in humans may reside preferentially at the DEJ, and not in IENFs, given the paradoxical loss of IENFS in some chronic pruritic conditions (Oaklander and Rissmiller, 2002; Maddison et al., 2008). In mice, molecular silencing of a population of TRPV1(+) primary nociceptive sensory neurons unmasked a chronic cutaneous scratching phenotype, possibly mediated by residual signaling from GRP(+) itch-sensing primary sensory neurons (Lagerstrom et al., 2010; Liu et al., 2010). Extending this work to humans, the location of GRP(+) nerves makes this population a prime candidate to selectively signal itch from the DEJ in some skin diseases where pain-only sensing nerves, such as in the epidermis, are preferentially lost—a hypothesis we are now actively testing. The Boston University IRB approved this study and did not require patient consent for the use of de-identified and otherwise discarded surgical tissue; the study was conducted according to the Declaration of Helsinki Principles.

Squamous cell carcinoma with osteoclast-like giant cells: a morphologically heterologous group including carcinosarcoma and squamous cell carcinoma with stromal changes.

Cutaneous squamous cell carcinoma (SCC) with osteoclast‐like giant cells (hereafter, osteoclastic cells) is very rare; eight cases have been reported since 2006. Whether the osteoclastic cells represents a reactive or neoplastic change remains a matter of debate. Osteoclastic cells are often observed in the sarcomatous component of cutaneous carcinosarcoma. SCC with osteoclastic cells is a heterogeneous condition that includes SCC with stromal changes containing osteoclastic cells (also known as osteoclast‐like giant cell reaction) and carcinosarcoma. In some cases, SCC with an associated osteoclast‐like giant cell reaction has been differentiated from carcinosarcoma based on the degree of cytologic atypia in non‐epithelial components. We summarized the clinical and histopathologic characteristics of 11 patients of SCC with osteoclastic cells, including our two cases of SCC with an osteoclast‐like giant cell reaction and one case of carcinosarcoma. The affected patients were old and more likely to be male (64%). Seven cases (64%) were in the head and neck. Moreover, multiple features of high risk SCC were observed, such as a tumor size greater than 2 cm (56%), moderate or poor differentiation (100%), recurrence (33%) and nodal metastasis (17%) after excision and immunosuppression (27%). Interestingly, half of the previously reported cases of SCC with osteoclastic giant cell reaction had histopathologic findings that were overlapping with those of carcinosarcoma.

Hyaluronic acid-induced alopecia: a novel complication.

Well-known complications of filler injections include pain, dyspigmentation, bruising, and rarely, iatrogenic blindness. Localized alopecia secondary to hyaluronic acid injections is a previously unreported complication of fillers. The clinical features and histologic evidence indicate vascular compromise as the etiology of filler-induced alopecia. Awareness of vascular occlusion as the cause of these complications affords appropriate targeted therapy.

Rituximab-Induced Serum Sickness-Like Reaction: A Histopathologic Viewpoint.

To the Editor: Serum sickness was first described by Von Pirquet and Schick in 1905 and is characterized by fever, an urticarial or morbilliform rash demonstrating leukocytoclastic vasculitis, arthralgia/arthritis, gastrointestinal disturbances, lymphadenopathy, and proteinuria. However, serum sickness–like reaction (SSLR) is used to describe a drug reaction also consisting of an urticarial or morbilliform rash, fever, and arthralgias but does not show evidence of cutaneous or systemic vasculitis. Numerous nonbiologic medications have been implicated as the cause of SSLR including antibiotics (such as amoxicillin, cefaclor, cephalexin, and trimethoprimsulfamethoxazole). Biologic immune modulators (such as infliximab, omalizumab, and rituximab) have also been associated with SSLR. However, the histologic features of SSLR caused by biologic agents have not been reported to date. We describe a 33-year-old woman on rituximab for thrombotic thrombocytopenic purpura and who presented with an urticarial rash with associated fever and arthralgia that developed 1 week after treatment (Fig. 1). The rash started on an upper extremity and spread asymmetrically to her trunk and lower extremities. Histologic analysis revealed papillary dermal edema, ectatic blood vessels, and a sparse, superficial-to-mid perivascular lymphocytic infiltrate with neutrophils, rare eosinophils, and neutrophils in blood vessel walls. The specimen lacked changes of leukocytoclastic vasculitis and lacked characteristic mild basal layer vacuolization with rare Civatte bodies seen in exanthematous (morbilliform) drug eruptions (Fig. 2). Histopathologic features of SSLR from this medication have not been reported to date. FIGURE 1. Serum sickness–like reaction. Multiple blanching wheals with associated, peripheral red flare (inset) with some admixed erythematous papules and annular plaques.

Melanocytic Nests Arising in Lichenoid Inflammation: Reappraisal of the Terminology "Melanocytic Pseudonests".

Abstract: Pseudonests or pseudomelanocytic nests represent aggregates of cells and cell fragments, including keratinocytes, macrophages, lymphocytes, and occasional melanocytes. Pseudomelanocytic nests in the setting of lichenoid inflammation can mimic atypical melanocytic proliferations. Several reports documented nonspecific staining of pseudonests with melanoma antigen recognized by T cells-1/Melan-A, which can be detected in the cytoplasm of nonmelanocytic cells. In contrast, nuclear stains, such as MITF and SOX10, avoid this nonmelanocyte cytoplasmic staining. The authors have previously proposed the term melanocytic pseudonests to describe junctional nests with numerous (>2) true melanoma antigen recognized by T cells-1/Melan-A, SOX10, and MITF in a nonmelanocytic lesion with lichenoid inflammation (unilateral lichen planus pigmentosus/erythema dyschromicum perstans). In this study, the authors report another case of this phenomenon arising in a different lichenoid inflammatory dermatitis (lichen planus). The immunophenotype and number of clustered true melanocytes indicate that these dermoepidermal aggregates represent true melanocytic nests and not pseudonests of any type. Therefore, the authors propose the revised terminology of “melanocytic nests arising in lichenoid inflammation” to describe this novel pattern of benign melanocytic reorganization or proliferation in a subset of lichenoid dermatitides. Because this phenomenon can mimic atypical melanocytic proliferations, clinicopathologic correlation is essential for the correct diagnosis.