A 68-year-old woman with a history of xeroderma pigmentosum was referred to our department three years prior for the treatment of basal cell carcinoma (BCC) on her face, which we surgically resected.

During periodic follow-up, a lesion with black and brown spots developed on her left cheek, and a malignant skin tumor was suspected. We performed excisional biopsy, and pathologically diagnosed it as a collision tumor of malignant melanoma and BCC. Collision tumors of malignant melanoma and BCC are rare and difficult to diagnose clinically. In order to diagnose a collision tumor, it is important to observe the entire lesion in detail via dermoscopy. [Skin Cancer (Japan) 2021 ; 36 : 16-20]

An 81-year-old man noticed a subcutaneous mass in his left groin on May, 20XX. He had no previous history of malignancy. The left inguinal lymph nodes were swollen, and positron emission tomography-computed tomography showed an accumulation of fluorodeoxyglucose.

Histopathological examination of the resected lymph node revealed lymph node metastasis of a well-differentiated squamous cell carcinoma (SCC). No primary lesion was found after systemic physical examinations. The diagnosis of inguinal lymph node metastasis of SCC of unknown primary lesion was made. An additional inguinal lymph node dissection was performed. There have been no signs of recurrence or metastasis to other organs for 17 months after the surgery.

Cancers of unknown primary lesions account for 1-5% of malignant tumors. Of these, SCC is extremely rare. Metastatic cancers of unknown primary lesions usually have a poor prognosis ; however, SCC has been reported to have a relatively good prognosis. Although it is very rare, patients with such malignancies should be followed up closely.[Skin Cancer (Japan) 2021 ; 36 : 21-25]

A 59-year-old woman presented with an itchy eruption on her head. She had previously been diagnosed with eosinophilic pustular folliculitis, which had been unresponsive to treatment. She was observed to have infiltrative erythematous facial lesions, nodules on her scalp associated with hair loss, as well as plaques and papules over her trunk and upper extremities. Histopathological evaluation of a skin biopsy specimen from a scalp nodule showed dense perifollicular infiltrates of atypical lymphocytes and eosinophils. Immunohistochemical evaluation of the infiltrate revealed that the cells were immunopositive for CD4 and immunonegative for CD30. The patient was diagnosed with folliculotropic mycosis fungoides and was initiated on treatment with topical corticosteroids, bexarotene, and electron therapy, followed by mogamulizumab, cyclophosphamide, doxorubicin, vincristine, and prednisone (CHOP) and cyclophosphamide, etoposide, procarbazine, and prednisone (CEPP) regimens, narrow-band ultraviolet B radiation, vorinostat, and oral prednisolone.[Skin Cancer (Japan) 2021 ; 36 : 26-32]

A 76-year-old woman presented with a red nodule arising from the surgical scar on her upper abdomen ; the scar was from a Caesarean section 51 years earlier. On examination, there was a red plaque, 2.5 cm in diameter, with exudate adjacent to the lower edge of the fistula. Black pigmentation and a 1-cm red nodule were seen over the plaque. The histological diagnosis was basal cell carcinoma (BCC). Magnetic resonance imaging showed that the lower edge of the fistula was below the line alba. The tumor and surrounding peritoneal adipose tissue were successfully removed under general anesthesia. Histological examination revealed the origin of the tumor cells from the normal epithelium of the fistula wall. BCC arising from a fistula of a surgical scar is extremely rare.[Skin Cancer (Japan) 2021 ; 36 : 33-37]

We report the case of a 53-year-old Japanese man who had undergone excision of in-transit melanomas on his lower extremities 3 years and 2 months after an initial surgery for plantar malignant melanoma but had suffered a recurrence. As the patient showed no response to the initial nivolumab therapy, we administered a dabrafenib/trametinib combination therapy, and complete remission was achieved after 3 months. However, the in-transit melanomas recurred after the treatment had been discontinued. Nivolumab therapy was therefore restarted in combination with radiotherapy, and thereafter local injection of interferon-β was performed, resulting in the disappearance of the in-transit melanomas. The present case suggests that a combination therapy with immune checkpoint inhibitors and local treatments such as radiation and interferon-β may exert various antitumor effects, thus improving the prognosis and local control of the melanoma.[Skin Cancer (Japan) 2021 ; 36 : 38-43]

Immune checkpoint inhibitors can cause various adverse effects. In particular, endocrinological adverse events have a delayed onset and may require continuous hormone replacement therapy. Diagnosing hypopituitarism proves challenging because of nonspecific symptoms at clinical presentation ; however, if left untreated, hypopituitarism may cause an adrenal crisis, with potentially fatal outcomes. We examined the clinical characteristics associated with hypopituitarism in five patients. All patients presented with symptoms of intense malaise, and three patients presented with hyponatremia. Oral corticosteroid therapy was administered in all patients and elicited a rapid improvement in the clinical condition. With regard to patient outcomes, hypopituitarism did not indicate a good prognosis in this patient group.

The management of hypopituitarism can be improved by early detection and systemic corticosteroid therapy. Fatigue and hyponatremia are frequent characteristics of hypopituitarism, and attention to these two clinical features can facilitate the early detection of hypopituitarism.[Skin Cancer (Japan) 2021 ; 36 : 44－48]

A 32-year-old woman had noticed a small tumor on her right cheek since 3 months which rapidly increased in size. It had become almost 20 mm in diameter and had been resected by another doctor 2 weeks prior. It had been histopathologically diagnosed as Merkel cell carcinoma. Imaging showed no obvious metastatic or other neoplastic findings. Therefore, she underwent a wider local re-excision and sentinel lymph node biopsy, both of which were negative for tumor cells. She had no history of excessive UV exposure or immunosuppressive status. Merkel cell polyomavirus was positive on immunostaining. She did not receive additional treatment, and no signs of recurrence were observed at her 2-year follow-up.

Merkel cell carcinoma is overwhelmingly more common in elderly people. Herein, we report a case of Merkel cell carcinoma in a 32-year-old woman that occurred due to Merkel cell polyomavirus. This is the youngest case of Merkel cell carcinoma to be reported in Japan.[Skin Cancer (Japan) 2021 ; 36 : 49-54]

A 72-year-old man noticed a subcutaneous tumor on his right shoulder about a month ago. An irregular, elastic hard, and reddish-purple tumor with a diameter of 4 cm was observed at the first visit. The pathological findings of biopsy showed that atypical spindle cells were arranged in bundles or herring bone appearance in the dermis, suggesting spindle cell sarcoma. CT scan did not detect regional lymphadenopathy and metastasis. The tumor was resected including trapezium muscle with a lateral margin of 30 mm. The pathological findings of resected specimens showed atypical spindle-shaped cells infiltrating the subcutaneous tissue and trapezius fascia. The tumor cells partially exhibited a fish bone appearance. Tumor cells were diffusely CD34 positive on immunostaining. COL1A1-PDGFB fusion gene was detected, and a diagnosis of dermatofibrosarcoma protuberans (DFSP) fibrosarcomatous variant was made.

It is considered that the detection of COL1A1-PDGFB fusion gene is useful for diagnosis of DFSP.[Skin Cancer (Japan) 2021 ; 36 : 55-59]

A 33-year-old man who did not have neurofibromatosis type 1 presented with a tumor on his back that had grown rapidly over the course of a few days. Initial examination revealed an erythematous tumor (21×20×10 cm). Magnetic resonance imaging identified it as a large hematoma, which was removed under general anesthesia following transcatheter arterial embolization. During surgery, another tumor was discovered within the hematoma and was concurrently resected. That tumor was pathologically diagnosed as a low-grade malignant peripheral nerve sheath tumor. An additional excision was immediately performed, and the patient was treated with radiotherapy (62 Gy X-ray). As of two years after surgery, no recurrence of the lesion has been observed. This case was rare because the majority of the tumor comprised a low-grade lesion resembling neurofibroma and because the tumor was suspected to have arisen from plexiform neurofibroma.[Skin Cancer (Japan) 2021 ; 36 : 60-64]

An 86-year-old female with erythema on her face and body was diagnosed with toxic eruption and treated with oral prednisolone. Five months later, she developed a reddish nodule on her right upper eyelid. Histopathologically, the eyelid lesion consisted of middle to large-sized lymphocytic cells as well as immunoblast-like and centroblast-like cells. Immunohistopathologically, the middle to large sized lymphocytic cells were positive for CD79a, PAX-5, and MUM-1, partially positive for CD20, and EBV-encoded small RNA were detected by in situ hybridization. The neoplastic cells with plasmacytic differentiation were positive for CD138 in some lesions. However, there was no difference in the expression of the kappa and lambda light chains. A diagnosis of EBV-positive DLBCL, NOS was eventually made.[Skin Cancer (Japan) 2021 ; 36 : 65-70]

A 91-year-old male was diagnosed with leprosy at 12 years of age. He had low ADL levels and was almost bedridden. He presented with erosions and crusts on his left cheek, which was treated as actinic keratosis by cryotherapy two years prior. The lesions had gradually enlarged and developed a tumorous nodule, which was diagnosed as squamous cell carcinoma by skin biopsy. Surgery or radiotherapy was considered as a treatment option, but conservative treatment continued at the previous hospital. The tumor increased further, and he was referred to our department. Physical examination demonstrated an ulcerative red brownish tumor measuring 12×10 cm in the left cheek. A whole-body computed tomography scan showed no enlarged lymph nodes or distant metastases. Although he had several risk factors including old age, anemia, decreased ADL, hypoalbuminemia, and pleural effusion, palliative surgical excision was performed for local control. However, he died of pneumonia five months after the operation.[Skin Cancer (Japan) 2021 ; 36 : 71-75]

A 51-year-old man presented with a 3-month history of a mass on his head. The mass gradually increased in size, and an incisional biopsy was performed. He was diagnosed with an apocrine mixed tumor and underwent marginal excision. Histopathological evaluation of the resected specimen revealed biphasic tumor cells, with luminal epithelial cells that formed a luminal structure and basal cell-like cells that formed a pseudolumen surrounding basophilic mucus material. We observed a cribriform pattern of proliferation with a combination of true and false lumens, involvement of surrounding tissues, multiple mitoses, necrosis, and perineural invasion. Immunohistochemical evaluation revealed tumor cells with immunopositivity for epithelial membrane antigen, α-smooth muscle actin, and calponin. Fluorodeoxyglucose-positron emission tomography did not reveal any other neoplastic focus in the body, and the patient was diagnosed with primary cutaneous adenoid cystic carcinoma. He underwent wide excision and skin grafting, 2 months after the initial surgery. No recurrence or metastasis occurred within 2 years postoperatively.[Skin Cancer (Japan) 2021 ; 36 : 76-80]

A 61-year-old female noticed a tumor in her left upper eyelid about one year prior. She underwent a biopsy at the ophthalmological clinic, and a malignant tumor was suspected. Physical examination revealed a 7 × 4 mm-sized pink-red nodule, with a smooth surface, relatively well-defined border, and eyelash defect inside. In the biopsy specimen, atypical tumor cells proliferated in lobules, forming irregular glandular structures from the dermis to subcutaneous tissue. Given that there was no distant metastasis, a preliminary diagnosis of primary adenocarcinoma of the eyelid was made. On histological examination, the tumor showed a decapitation-like pattern focally in Moll’s glands and was partially positive for GCDFP-15, with no sebaceous differentiation. Finally, a diagnosis of adenocarcinoma of Moll’s glands was made.[Skin Cancer (Japan) 2021 ; 36 : 81-85]

A 42-year-old woman underwent left-sided breast cancer resection and sentinel lymph node biopsy. The fibrous capsule of the lymph node contained a cluster of cells with homogeneous round-to-oval nuclei and sporangia containing abundant brown granules. Tumor cells were also present in the lumen of the adjacent lymph vessels. Although the tumor cells did not exhibit any abnormal mitotic images, there was a large number of tumor cells, and it was difficult to determine whether the tumor was benign or malignant. Immunostaining revealed S-100 positivity, Melan A positivity, HMB-45 minority positivity, PRAME negativity, and consistent 5-hmc expression. Resultantly, the patient was diagnosed with nevus cell aggregates in the lymph nodes. Although the presence of benign nevus cells in the lymph nodes is rare, it is important to differentiate this from malignant melanoma metastasis. However, it is difficult to establish a diagnosis based on the morphology and arrangement of the tumor, and caution is required. In the present case, we were able to confirm the diagnosis based on PRAME and 5-hmc staining.[Skin Cancer (Japan) 2021 ; 36 : 86-89]