Superficial CD34-positive fibroblastic tumor (SCPFT) is a recently described disease entity characterized by marked nuclear pleomorphism, low mitotic count, and diffuse CD34 positivity. It is a rare, distinctive, low-grade fibroblastic neoplasm. To date, only 44 cases have been reported in the English-language literature. Herein, we report two cases of SCPFT involving a 48-year-old male and a 22-year-old male with superficial tumors on the right and left thighs, respectively. Excision was performed in both cases. Histologically, both tumors showed spindle-to-epithelioid cells arranged in fascicular or sheet-like patterns. Most cells displayed granular or eosinophilic glassy cytoplasm, marked nuclear pleomorphism, and a low mitotic rate. On immunohistochemical staining, tumor cells were diffusely positive for CD34 and negative for S100 protein, smooth muscle actin, and desmin. After wide excision, neither patient experienced recurrence or metastasis after 16 months and 11 months of clinical follow-up, respectively. To the best of our knowledge, these are the first two cases of SCPFT reported in Korea. We believe these case reports would contribute to the clinicopathological understanding of SCPFT and assist clinicians in differentiating this tumor from other superficial soft tissue neoplasms.

Spindle cell lipoma is a rare benign neoplasm that features a mixture of evenly aligned spindle cells, mature adipocytes, and ropey collagen. Most cases of spindle cell lipoma are found in the subcutaneous tissue, and intradermal spindle cell lipoma is rarely reported. We present a case of intradermal spindle cell lipoma in a 46-year-old female who presented with a 0.7-cm flesh-colored and dome-shaped nodule on the right temple that had developed 6 years ago. This mass was excised, and upon histopathologic examination, an unencapsulated lesion was located in the dermis, which consisted of bland spindle cells, scanty mature adipocytes, rare lipoblasts, and ropey collagen bundles with prominent basophilic myxoid stroma. Immunohistochemical staining showed diffuse positivity for CD34, negativity for the S-100 protein, and loss of retinoblastoma protein expression. Based on these features, intradermal low-fat spindle cell lipoma was diagnosed. No evidence of local recurrence was observed 4 months after excision. Intradermal low-fat spindle cell lipomas are extremely rare and can easily be mistaken for tumors that have similar clinical and histopathological findings. Herein, we report a globally rare case of an intradermal low-fat spindle cell lipoma.

Background: Nodular hidradenoma is a relatively common benign cutaneous neoplasm, which usually presents as solitary intradermal nodule. In Korea, an extensive study on tumors with eccrine differentiation was performed in 2006; however, the study considered all eccrine tumors and detailed analysis of its differentiation was not performed. In addition, although most skin pathology textbooks classify it as a tumor showing eccrine differentiation, its differentiation remains controversial. Objective: This study investigated clinicopathological features of nodular hidradenoma in Koreans at a tertiary referral center. Methods: We retrospectively investigated 22 patients who presented with nodular hidradenoma at Yeungnam University Hospital between 2000 and 2021. Diagnosis was confirmed by histopathological examination in all the patients. Results: About half of the lesions were located on the head and neck area (45.5%), followed by the trunk (31.8%). Histopathological examination revealed that tumor cells in most of the cases consisted of cuboidal and clear cells; however, in some cases there were several specific modified cells such as clear cells (9.1%), squamoid cells (4.5%), and poroid cells (22.7%). Considering the morphological characteristic of tubular structures, most cases (90.9%) showed apocrine differentiation, and only 2 cases (9.1%) showed eccrine differentiation. Conclusion Considering the characteristics of cells and tubular structures constituting tumors, it is reasonable to consider nodular hidradenoma as a tumor with apocrine differentiation rather than with eccrine differentiation, which had previously been the predominant classification. Furthermore, there still is no distinct marker for determining whether cells differentiate into eccrine or apocrine tissues and further studies are therefore needed.

Methotrexate (MTX)-induced accelerated nodulosis (MIAN) reportedly occurs in patients with rheumatic arthritis receiving MTX therapy. However, it has also been reported in patients with other autoinflammatory conditions, such as systemic lupus erythematosus (SLE).A 38-year-old woman diagnosed with SLE presented with multiple movable, firm, fleshcolored nodules on both hands that had developed 3 years ago. She was taking oral medications, specifically hydroxychloroquine, azathioprine, and MTX. Histopathological examination revealed palisaded granulomatous inflammation, surrounded by histiocytes and lymphocytes, along the dermis to the subcutaneous fat layer. Fibrinoid degeneration was observed at the center of the granulomatous inflammation, and dermal mucin deposition was not observed. The patient was diagnosed with MIAN, and therefore discontinuation of MTX was recommended. Subsequently, the lesions almost completely disappeared with no signs of recurrence. MIAN exhibits clinicopathological features similar to those of rheumatoid nodules; therefore, it can be easily misdiagnosed. Herein, we report a case of MIAN in a patient with SLE to contribute to the accurate diagnosis and appropriate management.

Piloleiomyoma originates from the arrector pili muscles. Multiple piloleiomyoma lesions may occur, especially on the trunk and extremities. However, multiple lesions throughout the body are rare. We present a case of generalized cutaneous piloleiomyomatosis in a 72-year-old man who had numerous lesions throughout his body. Clinically, the patient presented with fixed and non-tender reddish to brownish papules and nodules mainly on the back and extensors of extremities. Punch biopsy was performed, and the specimen was stained with hematoxylin and eosin, revealing interweaving fascicles of cigar-like spindle cells on the upper dermis. On immunohistochemical staining, tumor cells were positive for smooth muscle actin. Based on these features, we diagnosed the patient with generalized cutaneous piloleiomyomatosis.

Background: Cutaneous metastasis (CM) is the spread of cancer cells from a primary site to the skin and is rarely the first sign of silent cancer. We investigated the clinicopathological characteristics of CM from internal malignancies in Korean patients treated at our institution over 20 years. Methods: The clinicopathological findings of 112 patients (62 females, 50 males) with CM diagnosed at Yeungnam University Hospital between 2000 and 2020 were retrospectively reviewed. Results: Mean patient age was 58.6 years (range, 26 to 87 years), and the most common primary cancer site was breast (74.2%) in women and lung (36.0%) in men. Ninety-six patients (85.7%) presented with CM after primary tumor diagnosis. CM from the lung or biliary tract usually occurred within 2 years of primary tumor diagnosis, whereas metastases from the breast and kidney occurred several years later. The chest, abdomen, and scalp were common sites of CM. Breast cancer usually metastasized to chest skin, while gastrointestinal tract cancers commonly metastasized to the abdomen. The scalp was a common location for CM from various tumors. The most common dermatologic presentations were nodules and masses. Immunohistochemical studies helped identify underlying malignancies when primary tumors were unknown. Conclusions The relative frequency of CM parallels the overall incidence of primary malignant tumors, and CMs usually occur at anatomic sites close to the primary tumor. CM can be diagnosed based on clinical, radiological, and histological features; however, immunohistochemical study is required in some cases.

Background: Cutaneous metastasis (CM) is the spread of cancer cells from a primary site to the skin and is rarely the first sign of silent cancer. We investigated the clinicopathological characteristics of CM from internal malignancies in Korean patients treated at our institution over 20 years. Methods: The clinicopathological findings of 112 patients (62 females, 50 males) with CM diagnosed at Yeungnam University Hospital between 2000 and 2020 were retrospectively reviewed. Results: Mean patient age was 58.6 years (range, 26 to 87 years), and the most common primary cancer site was breast (74.2%) in women and lung (36.0%) in men. Ninety-six patients (85.7%) presented with CM after primary tumor diagnosis. CM from the lung or biliary tract usually occurred within 2 years of primary tumor diagnosis, whereas metastases from the breast and kidney occurred several years later. The chest, abdomen, and scalp were common sites of CM. Breast cancer usually metastasized to chest skin, while gastrointestinal tract cancers commonly metastasized to the abdomen. The scalp was a common location for CM from various tumors. The most common dermatologic presentations were nodules and masses. Immunohistochemical studies helped identify underlying malignancies when primary tumors were unknown. Conclusions The relative frequency of CM parallels the overall incidence of primary malignant tumors, and CMs usually occur at anatomic sites close to the primary tumor. CM can be diagnosed based on clinical, radiological, and histological features; however, immunohistochemical study is required in some cases.