Histiocytoses are a heterogeneous group of disorders which are difficult to categorize because of overlapping clinical and microscopic features, and incompletely understood mechanisms of cellular origin and triggers of proliferation. Progressive nodular histiocytosis (PNH) is a rare non‐Langerhans cell histiocytic (NLH) disorder. We present the case of a 34‐year‐old woman with PNH, who has involvement of the back, head and neck, face, and uniquely, extensive involvement of the posterior pharynx and larynx, which has shown progressive worsening and deformity over a 7‐year course. Clinically it is best classified as PNH, although it microscopically closely resembles juvenile and adult xanthogranulomatosis. This study reinforces the concept that the NLH is a closely related group of disorders, possibly representing a spectrum of a single underlying process.

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An unusual case of malignant cylindroma of the scalp arising in a 79-year-old white female with multiple cylindromatosis is presented. The tumor apparently arose from a cylindroma and had features of spiradenoma. Multiple cylindromatosis is an uncommon hereditary autosomal dominant disease, which is characterized by multiple skin adnexal tumors like cylindromas and trichoepitheliomas and occasional spiradenomas. Cylindroma is an uncommon benign tumor, which originates from skin appendages and is most commonly found on the scalp and face with a strong predilection for middle-aged and elderly females. Although cylindromas are usually benign neoplasms, carcinoma arising in such neoplasms is rare with only sporadic reports in literature. Her family history was negative for a similar disease. The patient's main concern was painful lesions over her right ear that interfered with wearing of her glasses. The clinical, histological immunohistochemical features, and treatment are presented along with a review of the literature.