Chronic myelomonocytic leukemia (CMML) is a hematopoietic stem cell neoplasm exhibiting both myelodysplastic and myeloproliferative features. Cutaneous involvement by CMML is critical to recognize as it typically is a harbinger of disease progression and an increased incidence of transformation to acute myeloid leukemia. Cutaneous lesions of CMML exhibit heterogeneous histopathologic features that can be challenging to recognize as CMML. We describe a 67-year-old man with a 3-year history of CMML who had been managed on single-agent azacitidine with stable disease before developing splenomegaly and acute onset skin lesions. Examination of these skin lesions revealed a dense infiltrate of histiocytic cells morphologically resembling Langerhans type cells (lacking frank histopathologic atypia), and with the immunophenotype of an indeterminate cell histiocytosis (S100+ CD1a+ and langerin-). Given the history of CMML, next-generation sequencing studies were performed on the skin biopsy. These revealed a KRAS (p.G12R) mutation identical to that seen in the CMML 3 years prior, establishing a clonal relationship between the 2 processes. This case expands the spectrum for and underscores the protean nature of cutaneous involvement by CMML and underscores the importance of heightened vigilance when evaluating skin lesions of CMML patients.
HighlightsPG remains a diagnosis of exclusion and one not often seen by surgical specialties outside of Dermatology.It can mimic many other cutaneous conditions including bacterial infection, vascular occlusive disease and chronic non-healing wounds.Misdiagnosis often leads to mismanagement and aggressive surgical debridement.Recognizing the clinical features of PG and its pathergenic nature while ensuring timely management is fundamental to preventing severe destruction and deformity.
Chordoma is a rare primary bone malignancy of notochord origin, representing 1-4% of malignant bone tumors., Typically, chordomas follow a slow progressive course with aggressive local extension, multiple recurrences, and metastases. Of particular interest to this case, cutaneous metastasis is exceedingly rare. Diagnosis of this entity can be a challenge due to the rarity of chordoma, as well as the infrequent presentation of distant cutaneous metastasis and non-specific clinical skin findings. We report a case of a 61-year-old male with a history of sacral chordoma treated by wide local excision 8 years prior to presentation developed a nodule on his scalp for 6 weeks. Physical examination revealed a 1 cm rubbery, pink, shiny dome-shaped nodule on his left occipital scalp. Hematoxylin and eosin sections revealed a lobular dermal proliferation of small ovoid cells and larger physaliferous cells with hyperchromatic, displaced nuclei and finely vacuolated "soap-bubble" cytoplasm in a myxoid stroma. Immunohistochemistry of tumor cells showed positivity for both S-100 protein and pancytokeratin (AE1/AE3), while smooth muscle actin (SMA), P63, and CK7 were negative. Additionally, tumor cells stained positive for brachyury. The medical history, clinical presentation, histopathological appearance and immunohistochemical profile are consistent with cutaneous metastasis from sacral chordoma, known as chordoma cutis. This case illustrates the integral role of dermatopathology in the diagnosis of a rare and critical condition.
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