PO-01 | Pediatric nummular headaches: a case series and physiopathological and nosography considerations

Carola Meo¹*, Sofia D’Agostino¹*, Antonella Morea²*, Martina Tarantini²*, Giuseppe Giglia³, Maria Rosita Ruta⁴, Edvige Correnti⁵, Daniela D’Agnano², Giuseppe Santangelo⁵, Vittorio Sciruicchio², Vincenzo Raieli⁵ (*These authors contributed equally) | ¹Child Neuropsychiatry Unit Department, Pro.M.I.S.E. "G. D'Alessandro", University of Palermo, Palermo, Italy; ²Children Epilepsy and EEG Center, San Paolo Hospital, ASL Bari, Bari, Italy; ³Department of Biomedicine, Neuroscience and Advanced Diagnostics (BIND), Section of Human Physiology, University of Palermo, Palermo; ⁴Child Neuropsychiatry Unit, ASP 6, Palermo; ⁵Child Neuropsychiatry Department, ISMEP, ARNAS Civico, Palermo, Italy

Background: Nummular headache (NH) is a rare and often underdiagnosed primary headache characterized by a localized, well-circumscribed area of pain on the scalp. While documented in adults, its pediatric presentation remains poorly understood and scarcely reported.

Methods: We retrospectively analyzed six pediatric patients (aged 9–17) diagnosed with NH. For each case, clinical features including age at onset, pain localization and shape, associated symptoms, family history, treatment responses, and neuroimaging findings were evaluated. The diagnoses were assessed in light of the ICHD-3 criteria and compared to existing literature.

Results: Five patients presented with an episodic NH and one with a continuous form. The affected area ranged from 1 to 4 cm in diameter, with round, oval, and rectangular shapes reported. Allodynia was observed in two patients, and hypoesthesia in one. Four subjects experienced migraine-like features. One case was secondary to Langerhans cell histiocytosis. Neuroimaging was normal in all but one case. Therapeutic responses varied, with partial or complete improvement following NSAIDs, supplements (magnesium, PEA), or antiepileptics (gabapentin, carbamazepine). The occurrence of rectangular-shaped pain in two patients suggests a need for more flexible diagnostic parameters beyond the typical circular/oval definition in ICHD-3.

Conclusion: This case series highlights the clinical heterogeneity of NH in the pediatric population, including both episodic and continuous forms, variable pain shapes, and migraine-like features. The unusual rectangular shape observed in some cases challenges the current nosographic boundaries and suggests the need for a broader physiopathological understanding. A perception-centered hypothesis based on active inference theory may provide a more comprehensive framework. NH should be considered in the differential diagnosis of localized scalp pain in children, and neuroimaging remains essential to exclude secondary causes.