A Rare Case of Blastic Plasmacytoid Dendritic Cell Neoplasm in a Child Mimicking Lymphoma/Leukemia Cutis.

Blastic plasmacytoid dendritic cell neoplasm (BPDCN) is a rare tumor that affects elderly individuals and presents a poor prognosis. Skin is the most common site of involvement, accounting for 89% of the cases. Extracutaneous organs, especially bone marrow, lymph nodes, and peripheral blood, can be involved at the time of diagnosis. We report a case of BPDCN in a child, presenting with a cutaneous lesion mimicking lymphoma or leukemia cutis. The histologic findings revealed a dense diffuse infiltration by monomorphic agranular medium-sized blast cells with sparing of the grenz zone, whose first immunophenotypic profile raised the possibility of diagnosing B lymphoblastic lymphoma or leukemia. However, the absence of CD10 expression and strongly positive expression for CD4, CD56, CD45RA, and the plasmacytoid dendritic cell-associated antigens, including CD123, supported the definite diagnosis of BPDCN. The patient responded well to a systemic combination chemotherapy regimen, modified from the Associazione Italiana Ematologia Oncologia Pediatrica (AIEOP) protocol for anaplastic large cell lymphoma (ALCL), that differed from the established recommendation using ALL protocol. Owing to the patient's excellent treatment outcome, this regimen could represent an effective alternative regimen for BPDCN in children.

Cutaneous Involvement of Extranodal NK/T Cell Lymphoma, Nasal Type, a Clinical and Histopathological Mimicker of Various Skin Diseases.

BACKGROUND: Extranodal NK/T cell lymphoma, nasal type (ENK/T) with cutaneous involvement has various histopathological findings and diverse clinical manifestations. METHODS: A retrospective study of cutaneous involvement of ENK/T lymphoma between 2006 and 2018 was conducted. RESULTS: Twenty-two cases were eligible for this study. Twelve cases could be proven as secondary cutaneous involvement by ENK/T lymphoma, while the remaining could not be confirmed as primary cutaneous ENK/T lymphoma. The histopathological patterns included dermal and subcutaneous nodular infiltration pattern in 11/22 cases (50%), lobular panniculitis pattern in 6/22 cases (27.3%), interface dermatitis pattern in 4/22 cases (18.2%), and granulomatous dermatitis pattern in 1/22 case (4.5%). The median follow-up was 18.3 months. Overall, the one-year and five-year survival rates were 31.3% and 13.3%, respectively. CONCLUSIONS: A variety of histopathological patterns of cutaneous involvement by ENK/T lymphoma should be differentiated from other cutaneous lymphomas, dermatitis, and infection. When atypical medium or large-sized lymphoid cells are encountered within skin lesions, pathologists should realize these lesions can be ENK/T lymphoma, especially in cases with coexisting tumor necrosis or angioinvasion. A complete evaluation of the upper aerodigestive tract is mandatory to identify the occult primary site of ENK/T lymphoma before establishing primary cutaneous ENK/T lymphoma.

Parapsoriasis-A Diagnosis with an Identity Crisis: A Narrative Review.

Parapsoriasis is an uncommon inflammatory skin disease characterized by chronic patches that may be resistant to therapy. It was primarily introduced and classified 120 years ago, and the original classification incorporated parapsoriasis and pityriasis lichenoides under the umbrella term parapsoriasis. After a major change in classification, parapsoriasis now exclusively refers to small plaque parapsoriasis (SPP) and large plaque parapsoriasis (LPP). However, debates still frequently occur regarding various nomenclatures and classifications used by different authors. Moreover, parapsoriasis may progress to overt cutaneous lymphoma, most commonly mycosis fungoides (MF), and it is very difficult to distinguish these two conditions despite modern histologic and molecular testing techniques.As parapsoriasis is a rare disease, there is a lack of studies and clinical guidelines to assist physicians in clinical practice. In our comprehensive review, we review several aspects of parapsoriasis, from the history of nomenclature and classification, clinical characteristics, immunohistopathology, and advanced molecular techniques for the diagnosis of this condition, to the most current treatments. We also propose a scheme for distinguishing parapsoriasis from early-stage MF in this review.

Pigmented epithelioid melanocytoma (PEM) of the spine with compression fracture: case report.

BACKGROUND: Pigmented epithelioid melanocytoma (PEM) is a sporadic type of pigmented melanocytic tumor with uncertain malignant potential. PEM arises as a solitary neoplasm that predominantly occurs spontaneously in otherwise healthy patients. Due to its rarity, a gold standard treatment regimen does not exist; however, symptomatic cases should be managed with radiotherapy and surgery. CASE PRESENTATION: A 28-year-old Thai female presented with a sudden onset of back pain and weakness of the lower extremities during the postpartum period. Magnetic resonance imaging demonstrated abnormal soft tissue formation from T4 to T7; it extended to the vertebral bodies, left neural foramina, and posterior columns of T6 and T7. The patient underwent complete tumor debulking, decompressive laminectomy from T4 to T8, and posterior instrumentation from T3 to T10. The histopathology and immunohistochemistry suggested PEM. The patient fully resolved back pain after surgery. Nevertheless, as the patient re-presented with a neurological deficit a few months after the operative intervention, it was decided to perform a surgical resection via an en bloc vertebrectomy. At the one-year follow-up, although the patient reported continued improvement of her back pain, there was no motor power improvement. CONCLUSIONS: Spinal cord compression due to PEM is uncommon, especially in adults. Early diagnosis and treatment provide a good prognosis and help to regain lost neurological functions. Complete tumor removal and decompression of the spinal cord must be considered as a treatment strategy. Perioperative radiotherapy and chemotherapy have also been highlighted as treatment modalities for spinal tumors. With our reported case, early operative intervention coupled with radiotherapy produced satisfying outcomes.

Primary Cutaneous Lymphomas in Thailand: A 10-Year Retrospective Study.

BACKGROUND: Primary cutaneous lymphomas (PCLs) refer to cutaneous lymphomas that primarily develop in the skin with no evidence of extracutaneous disease at the time of diagnosis. The epidemiological and clinical data of PCLs in Thailand are lacking. OBJECTIVES: To evaluate the frequency, demographic data, and clinical characteristics of different subtypes of PCLs in a tertiary care university hospital. METHODS: In total, 137 patients with PCLs diagnosed in our hospital in 2008-2017 were retrospectively reviewed. RESULTS: Of the 137 patients, 57 (41.6%) were male and 80 (58.4%) were female (M : F = 1 : 1.4). The median age at diagnosis was 40 years. Most patients (134, 97.8%) had cutaneous T-cell lymphomas (CTCLs). Three patients (2.2%) had cutaneous B-cell lymphomas (CBCLs). The most common subtype was mycosis fungoides (MF) (67.9%), followed by subcutaneous panniculitis-like T-cell lymphoma (SPTCL) (21.2%), primary cutaneous anaplastic large cell lymphoma (pcALCL) (3.6%), lymphomatoid papulosis (LyP) (1.5%), primary cutaneous gamma/delta T-cell lymphoma (pcGDTCL) (1.5%), Sézary syndrome (SS) (0.7%), extranodal NK/T-cell lymphoma, nasal type (ENKTCL-NT) (0.7%), primary cutaneous peripheral T-cell lymphoma, not otherwise specified (pcPTCL-NOS) (0.7%), primary cutaneous diffuse large B-cell lymphoma, leg type (pcDLBCL-LT) (1.5%), and primary cutaneous follicle center lymphoma (pcFCL) (0.7%). Most patients with MF presented with early-stage disease (84.0%), with hypopigmented MF the most common variant (42.6%). CONCLUSIONS: Compared to earlier Caucasian and Asian studies, the present study revealed a higher proportion of CTCL patients with a younger age at onset and a female predominance. MF was the most common CTCL subtype, followed by SPTCL. More than 80% of MF patients were diagnosed at an early stage.

Follicular induction and CK20+ Merkel cells overlying cutaneous focal mucinosis.

BACKGROUND: Cutaneous focal mucinosis (CFM) or focal dermal mucinosis is a benign reactive process categorized as a primary mucinosis. Skin biopsy is essential for diagnosis, as the clinical appearance is often non-specific. Follicular induction is a phenomenon whereby the epidermis is induced by an underlying process to form primitive or mature hair follicles, and is commonly seen overlying dermatofibromas. Follicular induction has been rarely described in CFM. METHODS: We performed a retrospective histological review of lesions of CFM confirmed by skin biopsy from 2010 to 2015 in our department. RESULTS: We found that 11% (11/98) of CFM lesions showed follicular induction. Cytokeratin 20 (CK20) immunostaining was performed on all 11 of these biopsies that showed follicular induction and highlighted an increased density of CK20+ Merkel cells within the basaloid epidermal proliferations. CONCLUSION: As superficial basal cell carcinomas (BCC) often show a mucinous stroma around the basaloid islands, CFM with follicular induction may closely mimic a BCC histologically, particularly in superficial shave biopsies. Therefore, it is important that dermatopathologists be aware of this phenomenon. Furthermore, CK20+ staining within the basaloid epithelial proliferations may be helpful in differentiating CFM with follicular induction from a BCC.

Trachyonychia: Review and Update on Clinical Aspects, Histology, and Therapy.

Trachyonychia is a disorder of the nail unit that most commonly presents with rough, longitudinally ridged nails (opaque trachyonychia) or less frequently, uniform, opalescent nails with pits (shiny trachyonychia). The term trachyonychia refers to 'rough nails.' This article comprehensively reviews the clinical, histologic, and therapeutic aspects of trachyonychia. The authors' preferred evaluation and management strategies of trachyonychia are included.

Histiocytoid neutrophilic dermatitis, an unusual histopathology in neonatal lupus erythematosus.

The authors reported histiocytoid neutrophilic dermatitis in neonatal lupus erythematosus (NLE). One-month-old male infant presented with annular erythematous plaques at the face and trunk. Serologic studies revealed positive anti-ribonuclear protein antibodies (RNP) and antinuclear antibodies (ANA). Histopathology showed predominant myeloid lineage mononuclear cells admixed with segmented neutrophils. This finding is uncommon in cutaneous NLE. Cutaneous NLE and LE should be included in the differential diagnosis of histiocytoid neutrophilic dermatitis. Additional immunohistochemistry studies with clinical and serologic correlations are important to differentiate histiocytoid neutrophilic dermatitis from the other diagnoses, especially leukemic cutis in young patients.

Calcific panniculitis and nasopharyngeal cancer-associated adult-onset dermatomyositis: a case report and literature review.

Panniculitis is an uncommon cutaneous manifestation in dermatomyositis. It not only occurs in idiopathic dermatomyositis, but also rarely occurs in the setting of malignancy-associated dermatomyositis. Calcinosis cutis is also less likely to be found in adult-onset dermatomyositis. In malignancy-associated dermatomyositis, panniculitis can precede, concur, or follow the diagnosis of malignancy. We report the case of a 26-year-old Thai female with calcific panniculitis in the setting of adult-onset dermatomyositis associated with nasopharyngeal cancer. The clinical course of calcific panniculitis in our case was not parallel to the course of malignancy. Calcific panniculitis can appear many years after, despite the remission of the cancer. A thorough review of the previously reported literature is also provided.