Background/Objectives: Only anecdotal case reports or small case series have attempted to study the histomorphology patterns of leukemic infiltration. This study explored the possible association of leukemia cutis with, temporal course of disease, subtypes of leukemia, blast count, total leukocyte count, lactate dehydrogenase (LDH) levels, and histopathological patterns. Materials and Methods: Clinical and laboratory data were retrieved from the hospital information system. Selected cases were reviewed by two pathologists. Data in terms of demographics, clinical presentation, bone marrow findings, immunophenotype, and temporal course were recorded where available. Results: Twenty-three diagnosed cases of leukemia cutis were reported during the study period. There was no gender predilection with a wide age range (8–82 years). No particular trend was noted in relation to total leukocyte or bone marrow blast count. Common skin manifestations included multiple erythematous papular eruptions, frequently involving the skin of the limbs. All cases showed a consistently high serum LDH level. 11/23 (48%) showed cutaneous manifestation of undiagnosed leukemia or indicated worsening in a diagnosed case. The histological patterns varied from perivascular to diffuse dermal interstitial infiltration. In addition, subtle changes were seen in the form of fibrosis, thrombosis, and epidermotropism in 12%–50% of cases. The judicious use of a panel of immunohistochemistry was vital to establish a diagnosis. Conclusions: Leukemia cutis is a diagnostic challenge on histopathology due to lack of any specific pattern in absence of a clinical suspicion. Its diagnosis may be an indicator of undiagnosed leukemia or worsening in an already known case of leukemia.

Background: Seborrheic keratosis (SK) is the most common benign skin tumor. Dermatoscope is a simple noninvasive diagnostic tool. Although SK has been well recognized clinically, dermoscopically, and histopathologically, data regarding dermoscopic differentiation of different types of SK using the polarized (P) and nonpolarized (NP) modes of dermoscopy are inadequate. Objectives: The objective was to study the dermoscopic pattern of different types of SK under P and NP dermoscopic modes. Methodology: A descriptive study of 102 patients was carried out after ethical approval. All patients attending the dermatology outpatient department with lesions who were willing to participate in the study were included in the study after taking written informed consent. After a detailed history and examination, clinical and dermoscopic photographs were taken under the P and NP modes of a dermoscope attached with a smartphone camera. Biopsy of the same lesions was sent for a histopathology examination. Results: A total of 102 patients were studied. Females (58) outnumbered males (44). The most common clinical variant was common SK. The most common histopathological type of SK was hyperkeratotic followed by acanthotic type. Sharp demarcated border (75%) was the most common finding on dermoscopy in our study followed by fissure and ridges (63%), scales (54%), comedo-like opening (34%), cobblestone-like pattern (33%), moth-eaten border (17.7%), and cerebriform pattern (13.7%). Conclusion: NP mode helps in better visualization as well as depth perception, whereas P mode shows better color perception and sharpness of superficial as well as deep dermoscopic structures.

Background: Psoriasis is a chronic remitting and relapsing inflammatory disease, with a prevalence of 0.44%–2.5% and is characterized by T-cell-mediated rapid turnover of epithelial cells. Claudin-1 protein is an integral part of the keratinocyte tight junction and has a role in proliferation, differentiation, and cell adhesion. Aim: The aim of the study was to investigate the role of claudin-1 expression in relation to keratinocyte proliferation in psoriasis. Materials and Methods: Fifty cases of psoriasis were included in the study. Skin biopsies were subjected to claudin-1 and Ki67 immunohistochemistry. Claudin-1 expression in the basal and spinous layers was scored. Ki67 proliferation index was assessed. Seven cases of normal skin biopsies were also included as controls. Fisher's exact test was applied for statistical analysis. Results: The cases had a wide age range (14–78 years), with a mean of 46 years with a male preponderance (4:1). The basal cell layer showed a complete loss of expression for claudin-1 in 82% (n = 42). The spinous layer showed a decrescendo pattern of loss of claudin-1 expression in 96% (n = 48). The association of loss of expression of claudin-1 between the basal layer and spinous layer was statistically significant (P = 0.0229). The association of loss of expression of claudin-1 and high Ki67 proliferative index was also statistically significant (P < 0.00001). Conclusion: Our study showed consistent loss of expression of claudin-1 in the lower layers of the epidermis in psoriasis, which is also the site of intense proliferative activity. The cytokine soup released by the T-cells may be responsible for downregulation of claudin-1, which is one of the triggers for proliferation.

Histiocytic sarcoma is a rare hematolymphoid neoplasm originating from histiocytic cell clones. The lesions can occur in nodal or extranodal sites. A minority of cases present as unique cutaneous lesions. The definitive diagnosis is made by immunohistochemistry. The treatment depends on the severity of the disease. Herein, we report a case of histiocytic sarcoma in a 65-year-old female presenting with subcutaneous swellings and ulcerated coalescing nodules on the forearms and thighs with metastasis to the lung and treated with systemic chemotherapy.

Primary cutaneous mucinous carcinoma is a rare slowly growing neoplasm showing predilection for the head and neck, particularly the eyelids. On occasion, it affects other sites including scalp, face, ear, axillae, thorax, abdomen, groin, foot, hand, and vulva. Fewer than 150 cases have been reported in the literature. A 70-year-old man presented with an asymptomatic raised lesion over the left side of the face for 1 year. Microscopically, the diagnosis of primary cutaneous mucinous carcinoma was made, which was later confirmed by immunohistochemistry. Mucinous carcinoma of the skin has a relatively good prognosis with rare distant metastases, but has risk of local recurrence. Diagnosing it and differentiating it from metastatic carcinoma helps the clinician in further management of the patient.

Myxoid neurothekeomas are rare benign soft-tissue tumors that are considered to be of the nerve sheath origin. They usually occur in young most commonly on the upper extremities, head, and neck, with a predilection for the female population. Based on histomorphological appearance and immunohistochemical findings, there are three variants of neurothekeoma myxoid, cellular, and mixed type. The myxoid type is characterized by a greater degree of myxomatous changes, less cellularity with well-circumscribed spindle cells in the myxoid matrix, and stain positively for S-100. This has to be differentiated from several myxoid soft-tissue tumors. We present a rare case of myxoid neurothekeoma occurring in elderly females in the toe of the lower extremity.

Brooke–Spiegler syndrome (BSS) is a rare autosomal dominant inherited disorder characterized by multiple skin appendageal tumors. The predominant tumors can be a cylindroma, trichoepithelioma, and/or spiradenoma. Here we report this rare entity of Brooke–Spiegler syndrome in a 50 year old female on the basis of clinico-histopathological correlation. The gene responsible for this condition is cylindromatosis gene (CYLD1) which has been mapped on chromosome 16q12–q13. However, no mutation have been detected in CYLD gene analyzed in our patient which indicates lack of genotype–phenotype correlation in this patient.

Malignant glomus tumors (GTs) are very rare, and diagnosis requires consideration of specific histologic criteria based on a combination of criteria such as size of the tumor, degree of nuclear atypia, and the level of mitotic activity. GTs that do not fulfill the histologic criteria for malignancy but show at least one feature other than nuclear atypia should be classified as GT of uncertain malignant potential (GTUMP). We report the case of a 65-year-old female with a slowly progressing soft-tissue swelling in the right lower arm near the elbow joint that was successfully treated through wide surgical excision and histologically diagnosed as a GTUMP. On follow-up after 3 months, there was no evidence of recurrence or metastasis. Malignant GTs and GTUMPs are rare, and the nomenclature and classification of these tumors is controversial. These findings and the difficulty of differential diagnosis in a continuum between benignity and malignancy prompted our report.

Tuberous sclerosis complex (TSC) or Bourneville's disease is a genetic multisystem disorder of multisite hamartomas. Majority of TSC cases are sporadic. TSC typically presents in the first decade of life and has a reported incidence of 1:6000–12,000, with intracranial involvement in the form of cortical tubers or subependymal nodules. Tubers (potato-like nodules) are triangular-shaped lesions centered at the cortex/juxtacortical, with apex oriented “inward” toward the ventricles, on magnetic resonance imaging (MRI) of the brain. Tubers represent cortical glioneuronal hamartomas and consist of focal distortions in the cellular organization and morphology, which extend into the underlying (subcortical) white matter. Skin lesions with a history of seizures can be an eye-opener to diagnose angiofibromas and its variant, which can lead to further effective workup such as ophthalmoscopy and MRI of the brain to diagnose TSC, just like in our case.

Lymphangioma circumscriptum (LC) is a rare benign hamartomatous malformation of lymph vessel manifesting at birth or during early childhood. Angiokeratomas (AK) are vascular ectasia of papillary dermal blood vessels with secondary epidermal changes. AK and/or LC are one of the common vascular malformations associated with Klippel–Trenaunay syndrome (KTS). The simultaneous appearance of LC and AK has been reported rarely, and the occurrence of LC, AK, and port-wine stain in a patient of KTS is even rarer. Thereby, we report a case of co-occurrence of LC and AK in the same patient without systemic involvement.